Kelp Thing is an enemy of Mermaid Man and Barnacle Boy. The Kelp Thing has only appeared in Mermaid Man & Barnacle Boy VI: The Motion Picture. His real appearance was in the TV show. Kelp Thing was also portrayed in SpongeBob's remake of The Mermaid Man and Barnacle Boy Movie, as he wanted to steal Krabby Patties from the Patty Vault.
Kelp Thing's only known power is flying.
Kelp Thing's one true weakness is tow-away zones.
Kelp Thing wears a green suit, has a gold necklace, and he has eyes sticking out like that of a snail.