Leo the Party Monster appeared on Sesame Street during season 17 and season 18, first seen in Episode 2162. This loud monster is obsessed with partying -- any time, anywhere. He made subsequent appearances in Episode 2212 and 2222, as well as a sketch where he hosts "The Party Line" (First: Episode 2218) and playing a potato in a pageant sketch about foods.
The puppet used for Leo was later reworked as Ruby.
- Grover's Just So-So Stories: "How the Monster Got His Fur" (1987)
- Monsters, Monsters! (1987)
- Oscar's Silly ABC's and Other Stories (1987)
- On My Way with Sesame Street Volume 1 (1989)
- On My Way with Sesame Street volume "Just Pretend" (1989)