Spongehead and Boss are the primary antagonists of the first two Freddi Fish computer games, Freddi Fish and the Case of the Missing Kelp Seeds and Freddi Fish and the Case of the Haunted Schoolhouse.

Spongehead, the bigger shark, has a bad memory, as revealed when he leaves the bottles with the notes behind (so he could find his way back to where he hid the treasure), and later, Freddi Fish and Luther find them.

The smaller shark is never known by any name. Instead, he is simply called "Boss".