|Appeared in||Ghostbusters II|
|Played by||William T. Deutschendorf and Henry J. Deutschendorf II|
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. Dan 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.
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 which is the birth 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.
- 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 a recent interview, Sigourney Weaver mentions that in a copy of a Ghostbusters III script she read, Oscar does join the Ghostbusters. 
- 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.
- 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.