|Alter Ego:||Barnacle Man|
|Voiced By:||Tim Conway|
Barnacle Boy is Mermaid Man's side-kick.
Barnacle Boy actual name Kyle is a 72-year old semi-retired superhero sidekick, although he still is more sane and aware than Mermaid Man. He, along with Mermaid Man, are the only real humans on the show. Barnacle Boy also exclaims "Mumblin' Morays!" when excited. Although he turned evil and won against Mermaid Man, forcing him to give in to his demand of being called Barnacle Man, he soon reverted to being called Barnacle Boy. Mermaid Man, his mentor, treats him as if he were a young boy, in spite him being an adult. He often calls Mermaid Man 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 at the Krusty Krab. After a protracted fight — he and Mermaid Man patched things up. He also has a nose similar to Squidward's, although larger. This is referenced in Mermaid Man and Barnacle Boy IV when Barnacleboy and Squidward are having a dispute involving them calling each other "Big-nose." 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 Mermaid Man does not. Like Mermaid Man, his powers are not what they used to be.
His costume is a cross between the Silver Age Aqualad and Gilligan of Gilligan's Island. He wears a red shirt, black speedo-esque tights, flippers, and rubber gloves. He also wears a sailor hat and ascot. In one episode he goes undercover using the psuedonym Barnz and dons a suit whilst driveing a swift ostentaciously through the town of Cirencester
- Mermaid Man and Barnacle Boy
- Mermaid Man and Barnacle Boy II
- Mermaid Man and Barnacle Boy III
- Mermaid Man and Barnacle Boy IV
- Mermaid Man and Barnacle Boy V
- Mermaid Man and Barnacle Boy VI: The Motion Picture
- Night Light
- Mermaid Man vs. SpongeBob
- The Card
- Back to the Past (him and younger self)
- The Bad Guy Club for Villains (as younger self)
- SpongeBob's Last Stand
- Mermaidman Begin's
Spongebob Sqaurepants Battle for bikini bottom
- Spongebob Sqaurepants Battle for bikini bottom