Horace Stewart was once known as the finest chef in the East and his favorite niece was Olivia.  The Stewart family is famous for being from a lineage possessing inherited wealth. When he passed away, Horace left his mansion in Glen Cove, New York to Olivia. Horace's ghost manifested and searched fruitlessly for something he couldn't remember. To further complicate the matter, Horace had no idea he was a ghost.
Olivia wanted to sell her uncle's house, but needed to find a way to get rid of his ghost. After mistaking his niece and potential nephew-in-law John for real ghosts, Uncle Horace found the Ghostbusters' business card dropped by John and called them. Before the Ghostbusters arrived, The Sprite started haunting his house. When the Ghostbusters encounter Uncle Horace, they attempt to trap him until he reveals he was the one that called them. This also made Horace realize that he was a ghost and that he needs to find what he lost so he can peacefully disperse. When the Ghostbusters find and capture the Sprite, Horace finally remembers that what he was looking for wasn't a thing, but his niece. Before dispersing, Uncle Horace says goodbye to his niece and tells her he loves her one last time. After Uncle Horace made his final goodbye, John and Olivia decide not to sell his house and instead raise their children in it.
- Horace Stewart and his initial inability to realize he was a ghost reminded the Ghostbusters of a previous case that involved a hefty apparition on West 34th Street. 
- 34th Street is also a reference to "Miracle on 34th Street", which was a story of Kris Kringle that claims all through out the film to be Santa.
- Rabbit always gave Horace the strangest dreams. 
- On page four of Ghostbusters Issue #6, Uncle Horace makes a non-canon cameo at the diner.
- ↑ Ghostbusters Interdimensional Crossrip #347 - Maurice LaMarche/Voice Talent, Dr. Egon Spengler - December 4, 2017, 28:38-28:46 Maurice LaMarche says: "I used the Ed Wynn voice for a -- there was a touching episode about a ghost who only wanted to say goodbye to his niece."
- ↑ Olivia Stewart (2009).The Real Ghostbusters- "Who's Afraid of the Big Bad Ghost?" (1987) (DVD ts. 06:19-06:20). Time Life Entertainment. Olivia says: "There's Uncle Horace."
- ↑ Olivia Stewart (2009).The Real Ghostbusters- "Who's Afraid of the Big Bad Ghost?" (1987) (DVD ts. 06:55-07:04). Time Life Entertainment. Olivia says: "Before he took up haunting, Uncle Horace was the finest chef in the East. I was his favorite niece."
- ↑ Egon Spengler (2009).The Real Ghostbusters- "Who's Afraid of the Big Bad Ghost?" (1986) (DVD ts. 11:20-11:23). Time Life Entertainment. Egon says: "Remember that hefty apparition on West 34th Street? This spiky little fellow is just the same. He doesn't really know that he's..."
- ↑ Uncle Horace (2009).The Real Ghostbusters- "Who's Afraid of the Big Bad Ghost?" (1986) (DVD ts. 11:35-11:37). Time Life Entertainment. Horace says: "Rabbit always gives me the strangest dreams."