|Family:||* 1 son, 1 Daughter-in-law, 4 screaming grandchildren, Mermaid Man|
|Friends:||*Mermaid Man, SpongeBob, Patrick|
|First Appearance:||*Mermaid Man and Barnacle Boy|
|Voiced By:||Tim Conway|
Barnacle Boy is Mermaidman's side-kick.
Barnacle Boy (actual name Kyle) is a 68-year old semi-retired superhero sidekick, although he still is more sane and aware than Mermaidman. He, along with Mermaidman, are the only real humanoids on the show. His costume is a cross between the Silver Age Aqualad and Gilligan of Gilligan's Island. Barnacleboy also exclaims "Mumblin' Morays!" when excited. Although he turned evil and won against Mermaidman, forcing him to give in to his demand of being called Barnacle Man, he soon reverted to being called Barnacleboy. Mermaidman, his mentor, treats him as if he were a young boy, in spite him being an adult. He often calls Mermaidman an "old coot". In true sidekick fashion he takes the brunt of the physical comedy upon himself.
Barnacle Boy once became a villain briefly in Mermaidman and Barnacleboy V, teaming up with Man Ray and the Dirty Bubble following a dispute about a pipsqueak patty (a very small version of a Krabby Patty intended for children) at the Krusty Krab. After a protracted fight — and a painful parody of the International Justice League of Super Acquaintances with the regular cast — he and Mermaidman patched things up. Barnacle Man, as he likes to be called, gets a little more respect now (even though he cannot finish an adult-sized Krabby Patty). In the same episode, Barnacleboy mentioned he was so old he had hairs growing out of the wrinkles on his liver spots. He also has a nose similar to Squidward's, although larger.
This is referenced in Mermaidman and Barnacleboy IV when Barnacleboy and Squidward are locked in a battle of wits involving them calling each other "Big-nose." Barnacleboy also runs security at the Rock Bottom Museum.
In the video game, Battle for Bikini Bottom, it was revealed that Barnacleboy has a son, a daughter-in-law, and four "screaming" grandchildren.
Barnacleboy possesses powers similar to Mermaidman, though he lacks the belt powers. However, he does have "Sulfur Vision" (a form of heat vision) that Mermaidman does not. Like Mermaidman, his powers are not what they used to be.
Barnacleboy wears a white sailor cap, a black mask and a blue cape. He also wears a dark blue rubber gloves and boots and a red shirt and rubber black underwear.