Billy may refer to:
- Incidental 65 - An incidental that was named Billy in "Walking Small."
- Incidental 103 - An incidental that was named Billy in "Little Yellow Book."
- Incidental 107 - An incidental that was named Billy in "Professor Squidward."
- Incidental 151 - An incidental that was named Billy in "Krusty Dogs."
- Incidental 152 - An incidental that was named Billy in "Oral Report."
- Incidental 158 - An incidental that was named Billy in "Squirrel Jokes."
- Incidental 160 - An incidental that was named Billy in "The Yard Sale."
- Teen 1 - An incidental that was named Billy Fishkins in "The Chaperone."
- Teen 4 - An incidental that was named Billy Fishkin in "Whale of a Birthday."
- Incidental K1 - An incidental that was named Billy in "Penny Foolish."
- Billy (blue kid) - The birthday boy in the episode "Krusty Katering."
- Billy the Snail - The pet snail of Judge 3, as seen in the episode "Gary in Love."
- Billy Bob Star - The grandfather of Sam, Patrick, and Gary.
- Billy (baby) - The baby of Incidental 45 that first appears in the episode "Goo Goo Gas."
- Some of Plankton's cousins
- Billy West - A voice actor.
- Wei Bo-cin - Taiwanese actor whose name is Billy in English.