Ernie (or Jim) Huckler, better known by his superhero name Mermaid Man, is a semi-retired superhero who lives in Bikini Bottom. He and his sidekick Barnacle Boy are the stars of a show-within-a-show called The Adventures of Mermaid Man and Barnacle Boy, but they are also real superheroes within the SpongeBob SquarePants universe.
The two are now very old and currently reside at Shady Shoals Rest Home. However, SpongeBob SquarePants and Patrick Star, convinced them to come out of retirement