Garrett became an avid fan of the Ghostbusters ever since he saw them on TV. Garrett's father was recently diagnosed with cancer and couldn't spend as much time together with his son as he used to. Garrett had a hard time with the change. Garrett's mother Dr. Carla Parker spoke to Peter Venkman about a potential spot in his Ghostbusters 101 pilot program, a business venture designed to charge paying customers to experience what it takes to be a Ghostbuster in controlled conditions. She felt 101 would help him cope until something changed. They went to the Firehouse one afternoon and met Janine Melnitz and Kevin Tanaka. While Janine and Carla went over the paperwork, Kevin was tasked with introducing Garrett to Cait Banner, Evan Torres, and Zoe Zawadzki. He directed Garrett to follow him upstairs. Garrett asked Kevin how he lost his leg. Kevin inquired why he thought that. Garrett mentioned he saw a woman with a prosthetic in the hospital last week and she walked with the same kind of limp. Kevin was impressed and confirmed his left leg was amputated above the knee when he was seven years old because of a cancer diagnosis. Garrett revealed that's why his father was in the hospital. Kevin comforted Garrett and assured him cancer didn't get everybody and sometimes it only took a small piece. They made their way to the third floor where Jenny Moran was conducting a class. Naturally, Garrett asked if Jenny really was a ghost. Kevin added she was a very nice ghost then introduced him to his classmates. Kevin asked they not get Garrett slimed on his first day.
Cait and Zoe were eager to help orient Garrett and show him around the Firehouse. They wrapped their arms around Garrett's and asked Jenny for a break. Jenny decided to oblige them but instructed them to show Garrett what not to touch and to stay away from anything that could explode. They took him to the basement and demonstrated the Interspatial Teleportation Unit. Evan assured Garrett it was safe to put his hand through. He felt a breeze then the tentacle of a ghost on the other side grabbed his arm and pulled. Evan and Cait tried in vain to keep Garrett from moving forward. Zoe finally remembered how to turn off the machine. Evan, Cait and Garrett went flying. Drenched in ectoplasm, Garrett declared that was awesome. Janine was irate and read them the riot act. In the weeks between an incident with the Interspatial Teleportation Unit and the appearance of twin Statues of Liberty, Garrett Parker was sent on an errand to Ray's Occult Books. He left with a box piled to the brim with books and rolled up papers.
Garrett and the others were interviewed and scanned for any ectoplasmic residue from the incident with the teleportation unit. Garrett inquired what Kylie Griffin was looking for with the KUD meter. She reiterated they were looking for ectoplasmic residue so they could locate the ghost. Garrett insisted he washed it all off. Kylie was amused. Abby Yates told him ectoplasm seeped in and stuck around for awhile, causing Erin Gilbert to freak out. Garrett became concerned. Kylie assured him it was mostly harmless and they had a way of extracting it. She asked the teens if they brought their clothes from that day. Garrett was part of the group of 101 Cadets dispatched to Washington Square Arch to neutralize Ley Lines in order to cut off the ghost's connection. After Ray left with Peter, Garrett went to work with a Miniature Slime Blower. Evan called out to Garrett and told him he didn't have to cover every square inch with ectoplasm or else he might run out. Garrett asserted it was self-replicating and Ray said to be thorough. Some time later, the ghost of Mr. Parker called out to him and manifested. Garrett realized he died in the hospital. Mr. Parker recognized the irony that he didn't believe in ghosts and his current situation. Garrett contested the Ghostbusters already proved they do. Mr. Parker stated that's now how things worked but admitted the truth was hard to ignore now. He was glad they were right. Parker stated he was too weak to say goodbye the last time he saw Garrett and wanted to rectify it. He told his son he was a good man and was going to be watching over him then they hugged. Parker then asked Garrett to hug his mother for him. Garrett noted she didn't like hugs. Parker was sure she wouldn't mind this one time. Parker could feel his time was up and told Garrett he had some work to get back to. He dispersed.
Garrett and the rest of the pilot team were stationed at the Warehouse and tasked with keeping watch over the teleportation unit controls under the supervision of Egon Spengler of Dimension 68-E. Meanwhile, the Ghostbusters and several teams of dimensional counterparts headed into the multiverse to find ghosts that went missing from the Containment Unit.
- On the Regular Cover of Ghostbusters 101 #1, Garrett's clothing is a nod to Roland Jackson's stock civies on Extreme Ghostbusters.
- On December 21, 2016, Erik Burnham confirmed the new character on the regular cover of Ghostbusters 101 #1 was not the IDW canon's version of Roland Jackson but considered renaming him since Dan Schoening wanted to draw Roland. 
- On March 20, 2017, the character's name was revealed to be Garrett Parker in an interview.
- Garrett is autistic.
- Garrett is visually based on Will Smith's self-portrayal in "The Fresh Prince of Bel-Air".
- In the Dramatis Personae of Ghostbusters 101 #4, Garrett's biography reveals he is the son of one of Peter's psychologist colleagues.
- On page 3 of Ghostbusters 101 #5, panel 4, Garrett has on the blue cap from the Ghostbusters II Lobby Card No. 7.
- Garrett was mentioned in the 101 Cadets' bio in the 38th Crossing Over Virtual Trading Card, released on June 28, 2018. 
- On page 18 of Ghostbusters Crossing Over Issue #4, in panel 1, Garrett is carrying a box bearing Luis Antonio Delgado's 15 easter egg.
- Garrett appears in the upper right side of Cover B of Ghostbusters Crossing Over Issue #6.
- Ghostbusters 101
- Ghostbusters Crossing Over
- Kevin Tanaka (2017). IDW Comics- "Ghostbusters 101 #2" (2017) (Comic p.13). Kevin Tanaka says: "Everyone, this is Garrett Parker."
- Dr. Carla Parker (2017). IDW Comics- "Ghostbusters 101 #2" (2017) (Comic p.10). Dr. Carla Parker says: "But he's been obsessed with ghosts since he saw the Ghostbusters on TV, and I reached out because I thought this might help him cope until... well, until something changes."
- Dr. Carla Parker (2017). IDW Comics- "Ghostbusters 101 #2" (2017) (Comic p.9). Dr. Carla Parker says: "Garrett's father is... he's been very sick. They can't do much together as they used to, and Garrett has a very hard time with that kind of change."
- Garrett Parker (2017). IDW Comics- "Ghostbusters 101 #2" (2017) (Comic p.11). Garrett Parker says: "That's... that's why my Dad's in the hospital."
- erikburnham Tweet #1 12/21/16
- erikburnham Tweet #2 12/21/16
- Dynamic Forces "DF Interview: Erik Burnham brings Prime, ATC casts together in Ghostbusters 101" 3/20/17 Line reads: "They are: Cait Banner, Janine's niece; her friends Evan Torres and Zoe Zawadzki; and Garrett Parker, son of one of Peter Venkman's old psych classmates."
- Comicgeddon TV YouTube "IDW Comics - Ghostbusters 101 Creative Team - Interview with Dan Schoening and Erik Burnham" 57:16-57:40 5/31/17
- dannyschoening Tweet 4/29/19
- TomWaltz Tweet 6/28/18
- Egon Spengler (2017). IDW Comics- "Ghostbusters 101 #4" (2017) (Comic p.12). Egon Spengler says: "This happened after some of Ray's students accessed the Trans-Dimensional Portal."
- Walter Peck (2018). IDW Comics- "Ghostbusters Crossing Over Issue #5" (2018) (Comic p.1). Walter Peck says: "You have children operating dangerous equipment-probably unsupervised-I haven't been satisfactorily updated on an imminent threat, and I highly suspect things are rapidly descending to hell in a hand basket!"
- Kevin Tanaka (2018). IDW Comics- "Ghostbusters Crossing Over Issue #5" (2018) (Comic p.1). Kevin Tanaka says: "They're seniors."
- Jenny Moran (2018). IDW Comics- "Ghostbusters Crossing Over Issue #5" (2018) (Comic p.2). Jenny Moran says: "And, no, it's not one of the kids."