Mermaid Man is a superhero on the TV show Spongebob Squarepants. He is now in his seventies and has a sidekick named Barnacleboy, who is sixty-eight years old. Mermaid Man has shown to be quite high strung at times, which is evident by saying the word evil. he jumps up and starts shouting "Evil! Evil!" Barnacleboy is more sane than Mermaid Man, he tends to be the responsible one. however, both of them are frightened of spongebob, or "That Spongebob Kid."
Mermaid Man also has several other factors showing that he is retired, such as he cannot hit anyone with a waterball anymore due to his poor eyesight. He also has a big belly, due to no exercise. He has on occasion shown that he has a poor memory: He still thinks that he is a super hero. They both came out of retirement for a brief time for his TV show, which only shows them beating up litterers and playing checkers.