Slimer (also known as Onionhead , Little Spud, or The Green Ghost) was a ghost made up of pure Ectoplasm and the first ghost successfully captured by the Ghostbusters. Slimer is well known for his gigantic appetite and the slime he leaves behind when he passes through solid objects.
Slimer was a legendary ghost to all on the original staff of the Sedgewick Hotel. His usual territory was the twelfth floor, but his outings were usually non-violent and simply involved eating food. As a result, the hotel was able to keep a lid on the supernatural problems (for a while). For some reason, Gozer's approaching time of arrival provoked Slimer (and many other ghosts) into being much more active than usual. Eventually the staff couldn't keep the ghost a secret anymore and called the Ghostbusters. However, the Ghostbusters had not yet fully tested their equipment and weren't completely prepared for a full capture. Ray was the first to find Slimer, but missed him and Slimer escaped into the next hall, where he slimed Peter Venkman.
After many errant shots and the resulting destruction, Slimer flew into the Alhambra Ballroom where the Ghostbusters made another attempt at capture. Though Slimer is at first tossed around by some more missed shots, the Ghostbusters eventually manage to get him in the streams. Slimer was then caught in the Trap and put in the storage facility. However, he was released with the many other ghosts when the storage facility was shut down by Walter Peck. Slimer occupied a hot dog cart on at 1221 Avenue of the Americas in front of the Rockefeller Plaza. When the Hot Dog Vendor opened the cart, he was naturally shocked to see a ghost. After the Ghostbusters defeated Gozer and left Central Park West, Slimer was sighted in the area.
Slimer seemed to be a pet to the Ghostbusters, though it's unknown what he had been doing since the Ghostbusters were put out of business years ago. Slimer did resurface after the Ghostbusters started up again and had apparently gotten much fatter in the span of five years. Throughout the Vigo incident of 1989, Slimer interacted with Louis Tully. The two first met when Louis caught Slimer eating his lunch, to which the two of them fled in fear. On New Year's Eve, Louis decides to take up a Proton Pack and help the Ghostbusters. In an attempt to patch up their initial misunderstanding, Slimer helped an exhausted Louis by giving him a ride to the Manhattan Museum of Art (to which Louis wonders how he got his license). It seems likely Slimer had simply commandeered an abandoned bus from the havoc resulting from Vigo's Mood slime assault.
Ghostbusters: The Video Game (Realistic Version)
At some point, Slimer was recaptured and kept in a Paranormal Containment Research Tank in the Firehouse in the lobby. Egon Spengler used him for various paranormal studies (sometimes noted that this is a nod to The Real Ghostbusters shows take on Slimer). On Thanksgiving weekend 1991, Slimer was playing with Peter Venkman's ESP cards inside the Paranormal Containment Research Tank.
The Psi Energy Pulse damaged the Tank and Slimer escaped. The team finds him looking at the Containment Unit. When the Rookie takes a shot, Slimer avoids it and the Proton Stream hits the Unit, releasing the Sloth Ghost. Rookie and Ray pursued Slimer into the Sub-Basement but it escaped through a wall. After the Sloth Ghost was recaptured, the Ghostbusters headed to the Sedgewick Hotel on Ray's hunch Slimer would return to his old haunt. Sure enough, Slimer was found by Ray, Peter, and Rookie eating and drinking off someone's tray in front of Room 1218. Rookie took a shot but Slimer ran for it and tried to hide. Rookie roused him out and Slimer flew off towards the elevators where he descended back to the ground floor (but not before sliming Peter for a second time). Slimer is joined by Bellhop Ghosts. With renewed paranormal activity, Egon opts to split up. Rookie and Peter are tasked with recapturing Slimer. Peter believes he's feasting in the Alhambra Ballroom but the manager John O'Keefe bars entrance. Peter regroups and leads Rookie through the kitchen to access the other entrance to the ballroom. Rookie and Peter successfully traps Slimer.
Slimer is placed back into a working Paranormal Containment Research Tank when the team returns from Times Square. When Ivo Shandor shut down the containment grid, Slimer is among the escapees. After the Ghostbusters destroy Shandor and return to the physical plane, Slimer slimes Ilyssa Selwyn just as she and Peter are about to kiss in Central Park.
Secondary Canon History
Legion Mini Series
Slimer fell into the Ghost Legion who allied with Michael Draverhaven. From a hangar at the John F. Kennedy International Airport, Michael kept Slimer at his side as he coordinated attacks on New York City and the Ghostbusters. He used Slimer's Ectoplasm to construct a simple map of the city and to restrain Ray. When the other Ghostbusters arrived, Peter relished the chance to take another shot at Slimer. In the aftermath, it appears he evaded capture and fled the hangar with the rest of the ghosts.
Ghostbusters: The Video Game (Stylized Version)
He is more like a pet in this version evidenced by three dog food bowls with him in the Paranormal Containment Research Tank. Much like the Realistic Version, he escapes from his tank when the Psi Energy Pulse passes through the Firehouse. However, he only stays shortly to wave goodbye to the Ghostbusters then leaves for the Sedgewick Hotel. Peter and the Rookie recapture him, and he is placed into another research tank. When the ghosts are released from the Containment Unit, Slimer escapes again, but at the end of the game, Slimer doesn't slime Ilyssa. Instead, he reappears above the garage bay in the Firehouse. The credits roll while the Rookie(s) try to catch him again.
Ghostbusters: The Video Game (Stylized Portable Version)
He is much like the normal Stylized Version. However, the relationship as a pet/research subject wasn't suggested in dialog.
The sticky green slime machine from the Sedgewick Hotel.
Dealing with the Supernatural
- Ghost (must trap)
- Attacks: Melee, Range
- Weaknesses: Proton Stream
In the early 1920s up through 1938 or so, the Sedgewick Hotel played host to the Cult of Gozer. Supposedly, one of their incentives to draw in Gozer was to summon a hungry spirit that would wreck havoc on the American food supply which would have made them prime targets during World War II. However, a semi-corporeal manifestation of gluttony was conjured instead. The ghost stuffed their sacrifice, a live chicken, into its mouth. But it was a "hungry spirit" and could never sate its inhuman appetite. Luckily, the ghost was too lazy to roam outside and eat everything in sight. It remained anchored to the Sedgewick for decades. Documented hauntings by the ghost began in the mid-1920s. In 1951, someone ignored the Sedgewick's no room service policy on the 12th floor. Two bellhops took a cart to the floor, unaware of Slimer. Slimer quickly pounced on the cart and feasted. One of the bellhops soon resigned. In the 1980s, Slimer attacked some Honeymooners in their suite at the Sedgewick. He ate all their Primo Spiffies Cakes then slimed them.
During the initial encounter with the ghost, the Ghostbusters nicknamed it "Slimer" after it collided with Peter. It was eventually recaptured and placed into a Paranormal Containment Research Tank for study. After the "Shandor Incident," Slimer proved to be a problematic repeat haunter. He began terrorizing an apartment complex occupied by Alan Crendall, who thought it was a curse for what his Uncle Janosz Poha did in 1989. One week later, Alan told Winston about his problem. Winston and Peter investigated the following afternoon. While Winston scanned the Crendall's unit in room 426, Peter checked next door in 427. Peter ran into Slime r and flew through the wall into 426.
An hour or two later, Winston and Peter were still having an unusually difficult time in capturing Slimer. In a shocking display, Slimer was able to pull free from the Proton Stream. Using Winston as bait, Peter managed to ambush Slimer and trapped him. Slimer was returned to a Paranormal Containment Research Tank in the Firehouse. Egon later postulated the current uptick in P.K.E. made Slimer stronger than usual.
In the fall, after the Ghostbusters' trip across the nation, Egon used Slimer as a test subject for his studies on the Ghost Smashers. For several days, Egon experimented on explosive dispersal of mid-range ectoplasmic manifestations. Slimer proved to be an excellent test-subject. Egon concluded the time to reconstitution in a 180 cubic foot enclosure averaged at around three hours and 47 minutes. From that data, he extrapolated when the entities atomized by the Ghost Smashers would also reconstitute. When Egon wasn't looking, Peter dispersed Slimer for fun.
During the tail end of the Tiamat incident, the battle between the Ghostbusters and the Gozer-Tiamat-possessed Ray created another chance for Slimer to escape from the Paranormal Containment Research Tank. Three months later, Slimer was seen flying past Saks Fifth Avenue. At some point after the Saks Fifth case, Slimer returned to the Sedgewick Hotel. He was subsequently recaptured and returned to the Paranormal Containment Research Tank. During the Chi-You incident, Slimer snapped at Michelangelo. Ray demonstrated the effects of certain books on ghosts. He waived Fairfax's Demonologia at Slimer who recoiled and shielded his eyes. Once the demonstration was over, Slimer made faces at Ray. Ghostbusters from a parallel dimension were displaced by a ward of protection and Proteus' spell. They went into the Firehouse unaware it wasn't their own. Ray Stantz saw Slimer in the containment tank and went to release him. Egon Spengler observed Slimer's readings on his P.K.E. Meter and noticed they were different from their Slimer. It was too late. Slimer grabbed Ray and threw him aside. Egon, Peter, and Ray opened fire and wrangled him. Winston trapped him. Slimer was returned to the confines of the tank where he began consuming a cooked turkey.
Peter decided to play a prank on Egon, Ray, and Kylie. He hid a walkie talkie behind the research tank. As Peter instructed them, the 101 class inquired about the origin of Slimer. Egon Spengler and Kylie Griffin acknowledged there was a lot of theories about it. Kylie thought he was probably an employee in his past life since he was anchored to the hotel. She speculated he was probably a chef given his obsession with food and envisioned a scenario where he died of a heart attack after a complaint about his Beef Tartare left him incredibly angry. Egon disagreed. He speculated he could have been a vagrant due to his anti social behavior and a fixation on food. Ray didn't think the ghost was ever human and was simply a representational force given form. He cited from Funder's Cults of the Northeast. Peter proceeded with his prank and pretended to be Slimer on the walkie. Egon, Kylie, and Ray thought Slimer claimed he was once a king in his past life. They took the bait and scrambled to document what just happened. Peter thought of one more thing. Slimer "confessed" Ray fed him Egon's stash of snack cakes to see if they would digest differently. Egon was irate. Peter was amused with himself and paid off the teenagers for helping him. Slimer, while still in the tank, appeared on the Ghostbusters 101 commercial with Egon.
During a state of dimensional overlap, the Ghostbusters met another alternate team. Kevin Beckman was excited by his new surroundings. Egon Spengler told him if he was good, he could name the green ghost. Kevin decided on "Kevin Junior". As Jillian Holtzmann observed the properties of the research tank, Slimer screamed at her. Abby Yates mistook Slimer as their dimension's counterpart but Holtzmann reminded her they blew that one up during the Mercado Hotel battle. During the ghost retrieval mission in the prime dimension, Slimer of 80-C, with Lady Slimer, drove a shuttle to the Firehouse and dropped off the Ghostbusters of Dimension 11-W, Ghostbusters of Dimension 68-M, Ghostbusters of Dimension 68-Q, Jenny Moran, Slimer 68-R, Slimer 68-E, Slimer 68-Q, and Slimer 11-W. Jenny flew upstairs to the second floor to gets some notes while Slimer 68-R, Slimer 68-E, Slimer 68-Q, and Slimer 80-C looked at Slimer in the Paranormal Containment Research Tank. Slimer screamed at them. They got scared and hid behind Jenny then kissed Walter Peck at the same time.
Ghostbusters: Sanctum of Slime
Slimer randomly appears in certain levels (Level 1: Training Day, Level 2: Asylum Brawl, Level 3: River of Ooze, Level 7: Back to the Sedgewick, and Level 9: Lair of the Huge Spider) but leaves after some time or taking a few blasts from the players. He is never dispersed nor trapped in the course of the story.
Continuing from the first movie, Slimer actually stuck around the Ghostbuster headquarters. He apparently was feeling lonely and the Ghostbusters were the only ones who paid attention to him. He mainly stayed hidden until being drawn out because of his appetite. The Ghostbusters at first reacted negatively to him, but as he hung around they started to tolerate him and even treat him like a friend. Ray gave him the name "Slimer" (just to annoy Peter). Slimer was finally accepted as a pet ghost after helping the Ghostbusters stop the Anti-Ghostbusters. Throughout the years, Slimer aided the Ghostbusters whenever a ghost was needed for the situation. Because he helped the Ghostbusters, Slimer had a large number of problems of his own. Many ghosts considered Slimer a "traitor" amongst ghosts for his compassion with the humans. This often put Slimer on bad terms with many villains who faced the Ghostbusters.
For more information of the animated version of this character go to the animated article.
Ghostbusters (Beeline mobile game)
You capture Slimer once, at the start of the game. He somehow escapes the Containment Unit and just floats around. The player can tap on him for a daily reward.
Tobin's Spirit Guide
Fondly dubbed "Onion Head" he's haunted the HQ for years. Throws slimeballs around and provides daily rewards.
Ghostbusters: The Board Game
Ghost Card Information
- To Hit: 4 or higher, add a Stream
- To Trap: 4 Streams (from at least 2 Ghostbusters)
- When Hit: Moves 2 spaces towards that Ghostbuster.
- When Trapped: Place it on your Character Card.
- When Missed: Each adjacent Ghostbuster gets Slimed, then Slimer moves 2 spaces in a random direction.
- At the end of each round, Slimer moves 2 spaces toward the nearest Slimed Ghostbuster.
- If Slimer leaves the map, he re-enters the map on the opposite side of the map.
Impossible Mode Side A
- To Hit: 4 or higher, add a Stream
- To Trap: 4 Streams (from at least 4 Ghostbusters)
- When Hit: Moves 2 spaces towards that Ghostbuster.
- When Trapped: Place it on your Character Card.
- When Missed: Each Ghostbuster adjacent to Slimer gets Slimed, then Slimer moves 2 spaces in a random direction.
- Slimer's "To Trap" is increased by 2 for each Slimer on the Ghostbusters.
- At the end of each round, Slimer moves 2 spaces toward the nearest Slimed Ghostbuster.
Slimer is a "focused, non-terminal repeating phantasm or a class 5 full roaming vapor" made of pure Ectoplasm.
Prior to his first run-in with the Ghostbusters, Slimer had been haunting the five-star Sedgewick Hotel, specifically the 12th floor.
Slimer is well-known for a voracious appetite and leaving slime behind after passing through solid objects... especially humans.
Operations and Field Manual
This rascal is pretty fast! Be prepared to lose Line of Sight and lose attached Streams every so often when fighting Slimer. Proton Streams that hit, but do not Trap, Slimer trigger its "When Hit" ability. Since that makes it move 2 spaces towards you, it is best to engage tis Ghost from 3 spaces away. The Proton Stream that traps it does not trigger its "When Hit" ability. Instead, resolve its "When Trapped" ability. If you miss Slimer with your Proton Roll, it Slimes each Ghostbuster adjacent to it (you and any teammates), and then moves 2 spaces in a random direction. Roll the Movement Die and reference the PKE Meter to determine that direction. You are likely to lose LoS to Slimer when it runs. A tactical repositioning is sometimes more important than shooting at a Ghost. Slimer is one of the few Ghosts who will leave the map and not become permanently lost. When it leaves the map, continue Slimer's movement in that same direction, but emerging from the opposite side of the map, in a wrap-around style.
Throughout the first film, Slimer appears to lack intelligence and was all about getting a good snack. It was normally a shy ghost but was not afraid to slime when cornered. In the second movie, it appears that Slimer had become more intelligent and could drive a bus. So far, in the video game and cartoon he has grown in intelligence and seems to understand basic human concepts.
Slimer is classified as a focused, Non-Terminal Repeating Phantasm, or a Class 5 Full Roaming Vapor. And a real nasty one at that.
Ray posited Slimer is a representational force of gluttony given form with partially humanoid characteristics and tendencies.
Originally in the Ghost Smashers script, the tone of the movie was darker and Slimer wasn't as cute as he later became. In the opening sequence, the Ghost Smashers responded to a call from the Greenville Guest House regarding the discovery in the kitchen of gluttonous yellow mist or grotesquely altered human form --'free-repeating vaporous phantasm'. After chasing the apparition -- described as 'onion-headed' at one point -- through the rustic guest home, the Ghost Smashers cornered it in the basement, encircled it with nutrona beams and maneuvered it into a small collapsible trap. They charged $500, to which the Greenville Guest House proprietor balked at.
In the script for Ghostbusters, Slimer is never actually called by any name, so is never given one. The creature's original moniker was simply The Onionhead Ghost, which the film crew semi-officially dubbed him because of his horrible odor, which he used to scare a couple in a scene cut from the original movie. In early drafts, Slimer was vaguely described as an 'incredibly foul-smelling amorphous vapor'. Steve Johnson worked on hundreds of Slimer variations over a period of six months. At first, they asked for a "smile with arms" then started nitpicking, asking for ears, then no ears, less pathos, more pathos, a bigger nose, a smaller nose, more cartoony, and less cartoony. It wasn't until the day before the deadline for the design, in July 1983, that Johnson was told they wanted Slimer to look like John Belushi. With less than 24 hours, Johnson pulled out a stack of headshots of Belushi, did some cocaine, and went to work. During a bout of delusional paranoia that night, he thought Belushi's ghost came to help him finish the design by giving him words of encouragement and modeling. The ghost parted ways with him, warning that cocaine will kill him. The next day, the submitted design was approved. The 'green, potato-shape' was soon incorporated into the script. In total, three large scale Onionhead ghosts were created, each with a different expression and/or task. One was for smiling, one was for looking scared, and one was for drinking. A miniature was made for long shots of it flying around the hotel chandelier but it wasn't used. The Onionhead form was cast in the form of a foam latex suit but actual expressions were done with cable mechanisms. The body suspensions of the suit were based on old fashioned "dress hoops" so that a certain amount of "squash & stretch" could be achieved. The flexible jaw mechanics were made from stainless steel bands commonly used for strapping crates together. The bands allowed the mouth to be opened and closed and also flexed into extreme expressions.
For the live action set, in the scene where Ray spooks Slimer, a room service cart trailed after him. The cart was motorized and piloted from underneath by one of Chuck Gaspar's crew. Naturally, when the cart crashes, the driver is not present. The shot of Slimer phasing through the wall was shot at Entertainment Effects Group and incorporated optically later on.
During effects photography, the suit was worn by Mark Wilson. Wilson's legs were concealed with black velvet. A team of puppeteers dealt with facial expressions. Wilson worked with oversized props so the ghost would appear smaller after composited into live action.
When the cartoon series was produced, in response to the name much given to the character by audiences, the writers renamed the green ghost "Slimer", and the name stuck on all subsequent Ghostbusters properties (he was even named Slimer in the end credits of Ghostbusters II, but a character never actually referred to him as Slimer in the film canon until Ghostbusters: The Video Game), although he was referred to as "The Green Ghost" early in the related toy line. In later releases of his first figure, an extra label was applied specifying "Known as 'Slimer' in the 'Real Ghostbusters' TV show.
Slimer wasn't always a definite part of the Ghostbusters II script. It was a matter of considerable debate if he should appear at all. Slimer's appeal, luckily, was very universal among children thanks in part to the first movie and The Real Ghostbusters. Slimer was given a subplot and written into movie - Slimer would eat various foods in the Firehouse while Louis Tully would try to trap him then they would become friends. Michael Gross requested elements of the first movie and animated version of Slimer to be incorporated into the movie. Tim Lawrence and Thom Enriquez worked on a new design. Meanwhile, Bobby Porter was called into portray Slimer. Some of the technology and techniques used for Nunzio Scoleri were used for Slimer - the divided head construct, pneumatic jaws, SNARK and a fat suit - a departure from the first movie where he was hand puppeteered. Then Slimer was removed from the script. Porter was released.
Two weeks later, Slimer was back in the script and had a bigger role. However, Porter was no longer available. Effects coordinator Ned Gorman remembered working with Robin Navlyt on "Willow" and she was brought in. Surprisingly, she was the same height as Porter and fit into the suit very well. Chris Goehe and his mold shop crew made a full lifecast on her and Al Coulter worked on a new skullcap. The Slimer shoot was finished close to the first day of shooting. Michael Gross was onhand to push the crew to keep Slimer subtle and reduce any complicated approaches to moving him. Slimer's segments were deemed intrusive by preview audiences. During editing, Ivan Reitman decided to limit Slimer's role even though all scripted scenes were filmed and completed. Ultimately, Slimer's scenes were trimmed to two brief shots plus one during the end titles.
- During pre-production, Ivan Reitman remarked Slimer was sort of like Bluto in the film "Animal House" like the ghost of John Belushi. Dan Aykroyd never argued with that point. Since then, Slimer has been described as "The Ghost of John Belushi" by Dan Aykroyd in many interviews.
- Dan Aykroyd described Slimer as a vapor - a kind of confluence of stored up psychic energy, an accumulation of spirits that haunt the hotel who doesn't want to leave.
- Thelma Moss, of the Parapsychology department at U.C.L.A, told Harold Ramis Slimer was similar to a classic type of haunting known as 'hungry ghosts' - a ghost who just eats and drinks. Ramis admitted they didn't know about that when they wrote the script.
- Ivan Reitman provided all of the unearthly voices, such as Dana's demonic Zuul voice and Slimer, except for Gozer's.
- Slimer's ectoplasm was derived from methylcellulose ether -- a powdered thickening agent used in pharmaceuticals and food products.
- The sequence in the first movie when Slimer flies around the chandelier, it was originally supposed to be a miniature but it was too big for the shot. Due to time constraints, a peanut was spray painted green and used.
- As an afterthought in postproduction, Ivan Reitman came up with the idea to include Slimer in the last shot of the first movie.
- In the Novelization of the first film by Larry Milne and early scripts of the first movie, Silmer is described as being yellow. 
- Asides from being able to render himself incorporeal, Slimer appears to have low-level telekinetic ability. During his first encounter with Ray, Slimer flees, dragging a room service cart behind in tow. Which collides with the wall as he phases through it. This may also explain how he's able to work the foot pedals on the bus he commandeers to help Louis.
- In the Ghostbusters Role-Playing Game Series, Slimer's presence in the world of the living was credited as a side-effect of cult rituals. These cult rituals were likely performed in Slimer's case by the Cult of Gozer, lead by Ivo Shandor. Gozer, also known as "Lord of the Sebouillia", may-in turn-have influenced the name. Sebouillia in the Ukrainian language translates as "onion." Thus, Slimer's coined term, "Onion Head."
- In The Real Ghostbusters Marvel Comics Ltd series, Slimer was revealed to be the ghost of King Remils (an anagram of Slimer). The canonicity of this comic strip is doubtful though. 
- In the 1992 Annual by NOW Comics a profile of Slimer, stated, "In life he was an extremely greedy and obese man. After death he forgot all things about his life, even his own name, except the urge to continue eating."
- Slimer was originally going to be performed by Bobby Porter in Ghostbusters II, however Slimer's scenes were deleted therefore they let him go, and he got a different gig. Two weeks later, Slimer was re-added to the Ghostbusters II script, and because Porter was let go they had to find someone to replace him. Robin ended up being picked as she is about the same height as Porter, saving in refitting costs. 
- At the end of the theater version of Ghostbusters II, Slimer comes out from behind the Statue of Liberty and flies right into the camera just like how he did at the end of the first movie.  The VHS/DVD versions omits this and just ends with a pan up to the statue's head then a fade to black.
- In the Ghostbusters II deleted scene "Louis' Secret", Janine downplays the threat of Slimer to Louis.
- Slimer is shown in the trailer for "Ghostbusters: The Video Game," flying at the viewer in a manner similar to the end of the first movie, before a transition into the traditional Ghostbusters emblem.
- Slimer makes a cameo on Ghostbusters Issue #9 Cover RI-B, Spook Central variant.
- On Cover RI of Ghostbusters Issue #15, Slimer makes a cameo.
- On page nine of Ghostbusters Volume 2 Issue #9, there is a photo of Slimer on the center bottom section of Egon's board.
- On the Convention Cover of Ghostbusters: Get Real Issue #1, the Slimer makes cameo in top middle.
- Slimer appears on the front cover of the Ghostbusters: Get Real trade paperback.
- On the subscription cover of Ghostbusters: Get Real Issue #3, Slimer makes a cameo.
- In Slimer's character card in Ghostbusters: The Board Game
- The caption on the photograph quotes Ray's "Ugly little spud!" line from the first movie
- The caption on the Impossible Mode photograph quotes Ray's "A real nasty one!" line from the first movie
- The biography quotes Ray's classification of Slimer after he was trapped in the first movie
- The Sedgewick Hotel is mentioned
- On page 12 of Tobin's Spirit Guide, it is revealed the aftereffects of Slimer's presence is the persistent stench of rancid meat, increase in the heaviness of the air similar to stifling humidity, piles of chewed food, overturned furniture, and an unusual amount of exuded ectoplasm.
- Slimer appeared on the subscription cover of Ghostbusters International #6
- Slimer appears on the Regular and Subscription Covers of Ghostbusters Annual 2017.
- In the Ghostbusters Annual 2017, on page 39, Egon and Kylie make nod to all the abundance of theories about Slimer's origins.
- In the Ghostbusters Annual 2017, on page 42, Slimer's origin as a king was a reference to a story from The Real Ghostbusters Marvel Comic #22 when it was revealed he was King Remils in his past life.
- Slimer makes a non-canon cameo on the Credits Page of Ghostbusters 101 #1.
- On the Retailer Exclusive Cover of Ghostbusters: Funko Universe, Slimer makes a cameo.
- On page 12 of Ghostbusters 101 #3, in panel 1, Slimer is eating from a can of Pringles.
- In Ghostbusters 101 #3, Kevin Beckman named him Kevin Junior.
- Slimer appears on Cover C of Ghostbusters 101 #6.
- On the Cover RI of Teenage Mutant Ninja Turtles/Ghostbusters Volume 2 Issue #3, Slimer makes a cameo.
- On Cover B of Teenage Mutant Ninja Turtles/Ghostbusters Volume 2 Issue #5, Slimer appears.
- On Cover B of Ghostbusters Annual 2018, Slimer appears at the bottom between Samhain's Two Goblin Minions.
- On Cover RI-B of Ghostbusters Crossing Over Issue #1, Slimer eats from a cart like in the first movie.
- On Cover RI of Ghostbusters Crossing Over Issue #4, Slimer appears.
- On July 17, 2018, Tom Waltz posted Crossing Over Virtual Trading Card #43, The Green Ghost.
- On page 2 of Ghostbusters Crossing Over Issue #5, in panel 3, the Slimer of Dimension 80-C has on a hat like Slimer wore at the end of Ghostbusters II.
- Slimer appears in the upper right side of Cover B of Ghostbusters Crossing Over Issue #6.
- Slimer appears in Cover RI of Ghostbusters Crossing Over Issue #6.
- Slimer appears in Cover RI of Ghostbusters Crossing Over Issue #7.
- Slimer appears on Cover RI of Ghostbusters Crossing Over Issue #8.
- Slimer appears on the IDW Convention Variant cover of 35th Anniversary: Ghostbusters.
- Slimer appears on Cover B and the Fan Expo Dallas Cover of Transformers/Ghostbusters Issue #1.
- Ghostbusters II
- Ghostbusters: The Video Game
- IDW Comics
- "Past, Present, and Future"
- Cover A
- "Tainted Love"
- Cover RI
- "What in Samhain Just Happened?!"
- Regular Cover
- IDW Publishing Comics- Haunted Holidays TPB
- A reuse of "Past, Present, and Future" Cover A
- "Ghostbusters: Infestation 1"
- Cover RI B
- At least two covers
- Cover RI B
- "Ghostbusters: Infestation 2"
- Cover A
- Cover B
- Volume One
- Volume Two
- Teenage Mutant Ninja Turtles Ghostbusters
- Ghostbusters Get Real
- Ghostbusters Annual 2015
- "The 12th Floor"
- Volume Three
- Ghostbusters Annual 2017
- The Origins of Slimer
- All That Glitters
- Ghostbusters 101
- Ghostbusters Crossing Over
- "Past, Present, and Future"
- Insight Editions
- IDW Comics