Billy is a disambiguation. It may refer to:
- Billy (brown fish), a fish that appears in "Squirrel Jokes".
- Billy (lime fish), a fish that frequents the Krusty Krab.
- Billy (purple kid), a child as seen in "Penny Foolish".
- Frankie Billy, he is seen in "Professor Squidward," and in other episodes.
- Billy the Snail, pet of Brad, as seen in "Gary in Love."
- Billy the Orca, a killer whale seen in "SpongeGuard on Duty."
- Billy Fishkins, a fish seen in "The Chaperone" and "Don't Look Now."