In late 1989, while on the way back to their apartment, Dana rode Oscar's baby carriage over Psychomagnotheric Slime. Just outside the apartment, she spoke to Frank the Superintendent and took most of her focus away from Oscar. The slime animated the carriage and it rolled away. Despite bystanders coming to Dana's aid, the carriage and Oscar avoided capture. The carriage went right into an intersection on First Avenue and stopped in the middle of the street just before a bus passed by in the next lane. Dana grabbed Oscar and held him close to her. Dana went to see Egon Spengler and he agreed to investigate along with Ray Stantz. Peter Venkman found out and came along with them to examine Oscar. Egon and Ray conducted a precursory medical examination that included the Gamel and Pross Infant Acuity Test and Apgar Score. Egon confessed the only near-pediatric experience he had to this point was on a chimp. While Egon and Ray checked out Oscar's bedroom, Peter was tasked with getting a stool sample. Instead, Peter played with him and got Dana to get the sample.
Vigo commanded Janosz Poha to bring him a child to use as a host body in his resurrection. Janosz went to Dana's apartment the night Ray, Peter, and Egon caused a black out. Dana kindly refused to let him in after he inquired about Oscar. Some time later, when Dana was about to give Oscar a bath, Psychomagnotheric Slime seeped into the bathtub and tried to grab him. Dana took Oscar and ran to Peter's apartment. Peter made an ad hoc diaper from a sweater he got from a girl who got it from Joe Willie Namath. Peter soon convinced Dana to go out for dinner with him while Janine Melnitz babysat. Louis Tully helped out. They fed him some French bread pizza and Louis put Oscar to sleep with his take on "Snow White and the Seven Dwarfs."
Oscar was kidnapped by Janosz on New Years Eve. While out on the window ledge, Oscar was grabbed by Janosz, in an ethereal form and taken to the Manhattan Museum of Art. Dana followed but was captured and Oscar was returned to the altar in front of Vigo. Janosz attempted Dana to be his wife and raise Vigo as their son. As midnight drew near, Vigo began to slowly possess Oscar. Fortunately, the Ghostbusters arrived in the Statue of Liberty and intervened. Dana took Oscar and disrupted the possession. Vigo refused to give up and attacked. Peter hid Oscar then helped the others confront Vigo but they were immobilized. Luckily, the singing from bystanders outside weakened Vigo. He dropped Oscar and returned to his painting. Peter caught Oscar in time and returned him to Dana. The Ghostbusters made their final stand against Vigo and destroyed him. The painting then showed an image of the Ghostbusters in robes standing over Oscar.
Secondary Canon History
Oscar began attending PS 9, Sarah Anderson School, located on 100 W 84th Street. One of his teachers was Miss Runyon. He also began taking Karate lessons and was set to participate in a tournament on March 8. He recently won PS 9's "All Star Award" for sportsmanship. Oscar began to spend time with his biological father despite Dana's mother's reservations. At the conclusion of the Tiamat incident, Oscar returned to Dana's apartment from visiting his father. None the wiser about what transpired, Oscar found a birthday card from Peter waiting for him - along with a new Jets jersey.
Oscar has the same personalities as all babies. He appears to be very calm when in the presence of his mother and her friends. He is also very frightened of Vigo, as evidenced by his constant screaming.
His last name was never revealed in any source about Ghostbusters, but fan sites have been known to give him the last name Wallance (After Wallance who some fans speculate to be his father) and later as Venkman (after Peter Venkman, who marries Dana after the movie).
However, none of this has been proven in official Ghostbusters Canon.
- In the Ghostbusters II August 5, 1988 draft, Oscar is a baby boy who has no name throughout the script. He is the son of Lane Walker and Jason Locke (Vigo).
- The baby is stated to be nine months old and in the movie, Oscar is about eight months old.
- Louis gave the baby about 400 milliliters of milk whereas in the movie, Janine and Louis give him French bread pizza.
- It is a tremor and Jason Locke (Vigo) who influences the baby to pull himself into a standing position, then climb out of his crib and walk across the floor to an open window.
- According to Ray, Oscar was 24 inches, approximately 18 pounds and about eight months old when he and Egon examined him.
- Since he was about eight months old, Oscar was born in the spring of 1989.
- It has been speculated that the Violinist is the father of Oscar:
- In NOW Comics The Real Ghostbusters starring in Ghostbusters II part 1 he is depicted as a toddler in age.
- Oscar makes a cameo on the back cover of Ghostbusters Volume 3: Haunted America as part of a homage to the painting from the end of Ghostbusters II.
- When asked in 2011 if they'd be up for playing Oscar again in Ghostbusters III, Will Deutschendorf and Henry Deutschendorf said that they doubt that they'd be able to act well enough, and would bring down the movie as a result. However, they would be up for a cameo appearance. Yahoo! UK Article 2/10/14
- Dan Aykroyd said that one of his rejected scripts for Ghostbusters III had Peter going on a second honeymoon with Dana, and that the rest of the Ghostbusters were to keep an eye on Oscar, who would have been in his early to mid teens. Oscar would become a junior member of the team. 
- In an interview, Sigourney Weaver mentions that in a copy of a Ghostbusters III script she read, Oscar does join the Ghostbusters. In July 2016, Ivan Reitman corroborated it and stated the new group of Ghostbusters would have been led by Oscar.
- In an interview with Rolling Stone in July 2016, Ivan Reitman commented Oscar was probably Dana and Peter's son, although it's not made clear in the screenplay.
- Sadly, on June 14, 2017, Hank Deutschendorf committed suicide by hanging. He was 29 years old.
- On page 1 of Ghostbusters Year One Issue #2, Bob Douglas's precognitive dream is of the events of Ghostbusters II and he alludes to Vigo and Oscar.
- IDW Comics
- Ongoing Series
- Volume 2
- Issue #13
- Mentioned by Dana Barrett on page 14
- Issue #14
- Issue #18
- Issue #20
- Mentioned on page 24
- Issue #13
- Volume 2
- Ghostbusters Year One
- Ongoing Series
- Insight Editions
- Dana Barrett (1999). Ghostbusters II, Chapter 1: Start (1989) (DVD ts. 01:57). Columbia Pictures. Dana Barrett says: "Oscar!"
- Aykroyd, Dan & Ramis, Harold (1988). Ghostbusters II (August 5, 1988 Draft) (Script p. 10). "Paragraph reads: "Venkman is clowning with a very cute nine-month-old BABY BOY, holding the baby over his head and pressing his nose into the baby's belly, pretending that the baby is attacking him."
- Aykroyd, Dan & Ramis, Harold (1988). Ghostbusters II (August 5, 1988 Draft) (Script p. 66). "Louis Tully says: "He started crying a little so I have him about 400 milliliters f milk and he went right back to sleep."
- Aykroyd, Dan & Ramis, Harold (1988). Ghostbusters II (August 5, 1988 Draft) (Script p. 65). "Paragraph reads: "The tremor sends a slight vibration through the crib. The baby opens it's eyes and miraculously sits up. Then, as if motivated by some powerful and supernatural force, he grabs the safety bars of the crib, pulls himself to a standing position, climbs nimbly over the side and drops silently to the floor. He cranes his neck to cheek for any movement in the hallway, then walks across the floor to the open window."
- Dana Barrett (1999). Ghostbusters II, Chapter 5: Investigating Oscar (1989) (DVD ts. 16:47-16:54). Columbia Pictures. Dana Barrett says: "24 inches in length. Subject weighs approximately 18 pounds and is about eight months old."
- Recording of The Arsenio Hall Show 6/14/1989, Sigourney Weaver, 2:04-2:18Sigourney Weaver says: "And I've, um, actually all the characters five years later have sort of been down and out a little bit and, um, I've gotten married, I think, to the guy who used the nose spray in the first Ghostbusters and it didn't work out and so I got a divorce but I have this little baby."
- Joe Medjuck (2005). Ghostbusters- Commentary (2005) (DVD ts. 43:10-43:19). Columbia TriStar Home Video. Joe Medjuck says: "I've always presumed this is who Sigourney married - when she has a child in the second one. The Violinist. "
- Ivan Reitman (2005). Ghostbusters- Commentary (2005) (DVD ts. 43:15-43:19). Columbia TriStar Home Video. Ivan Reitman says: "Yes, yes, the Violinist. "
- Rolling Stone "Ivan Reitman: Why We're Still Talking About 'Ghostbusters' 30 Years Later" 7/6/16 "Ivan Reitman says: "Aykroyd, Ramis, and I worked on another draft of the film with two other writers, Lee Eisenberg and Gene Stupnitsky. We had a very good script that was a more traditional sequel idea. It was the passing of the torch from the original Ghostbusters to a new group led by Oscar, the little baby in the second movie."
- Rolling Stone "Ivan Reitman: Why We're Still Talking About 'Ghostbusters' 30 Years Later" 7/6/16 "Ivan Reitman says: "I loved the sequences between Sigourney Weaver and Bill Murray and what's probably their baby, Oscar, although it's not made clear in the screenplay."
- Janine Melnitz (2014). IDW Comics- "Ghostbusters Volume 2 Issue #14" (2014) (Comic p.5). Janine says: "I got the card last Christmas. With the photo of Oscar... It seems like yesterday he was the cutest little baby..."
- Dana Barrett (2014). IDW Comics- "Ghostbusters Volume 2 Issue #14" (2014) (Comic p.10). Dana says: "Yes, well, the second time it was my son, but--"
- Peter Venkman (2014). IDW Comics- "Ghostbusters Volume 2 Issue #18" (2014) (Comic p.16). Peter says: "Anytime the guys and I took something big down, the Paparazzi would, like, descend... and that wasn't good for you, and it wasn't good for the kid. How's he doin', by the way? Did he get the jersey?"
- Dana Barrett (2014). IDW Comics- "Ghostbusters Volume 2 Issue #18" (2014) (Comic p.17). Dana says: "Of course. I--he misses you."
- Bob Douglas (2020). IDW Comics- "Ghostbusters Year One Issue #2" (2020) (Comic p.1). Bob Douglas says: "Like just last night I dreamed this giant painting was trying to kidnap a baby, and – wait, you're still paying me for this interview, right?"
- Narrator (2016). Insight Editions- "Tobin's Spirit Guide" (2016) (Book p.64). Paragraph reads: "Vigo's initial plan was to inhabit the physical form of museum employee Dana Barrett's infant son, Oscar."