Jack is a disambiguation. It may refer to:
- Angry Jack, the manager of Angry Jack's Shell Emporium.
- Jack, a snail who appears in "Sanctuary!"
- Jack Kahuna Laguna, a surfing legend.
- Jack M. Crazyfish, a big purple fish who appears in the episodes, "Blackened Sponge" and "20,000 Patties Under the Sea."