Billy is a disambiguation. It may refer to:
- Billy (brown fish) - A fish that appears in the episode "Squirrel Jokes."
- Billy (lime fish) - A fish that is frequently seen in the Krusty Krab.
- Billy (purple kid) - A child seen in the episode "Penny Foolish."
- Billy (blue fish) - The birthday boy in the episode "Krusty Katering."
- Frankie Billy - An olive-green fish.
- Billy the Snail - The pet snail of Brad, as seen in the episode "Gary in Love."
- Billy the Orca - A killer whale seen in the episode "SpongeGuard on Duty."
- Billy Fishkins A fish seen in the episodes, "The Chaperone" and "Don't Look Now."
- Baby Billy - The baby of Shubie that first appears in "Goo Goo Gas."