Barnacle Boy

Barnacle Boy (real name Kyle) is the 68-year old (revealed in "Mermaid Man and Barnacle Boy V") semi-retired superhero sidekick of Mermaid Man. He is voiced by Emmy Award-winning comedian and actor, Tim Conway. He, along with Mermaid Man, are the only real humans to appear multiple times on the show (excluding Patchy the Pirate and other characters appearing in his segments). He is a parody of both Aqualad and Robin, and his costume is a cross between the Silver Age Aqualad and Gilligan of Gilligan's Island.

Barnacle Boy is thin, bald, has large nose similar to Squidward's, and 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 shorts. Being younger, he is more sane and self-aware than Mermaid Man. However, Barnacle Boy is also more cranky and rude. He often calls Mermaid Man an "old coot".

Barnacle Boy possesses powers similar to Mermaid Man, though he lacks the belt powers. Barnacle Boy also has "Sulfur Vision" (a form of heat vision), which Mermaid Man has never been shown to have. Like Mermaid Man, his powers do not work as well as they used to.

Despite being a senior citizen, Barnacle Boy is still treated like a child by his mentor, much to his disdain. In "Mermaid Man and Barnacle Boy V", when Mermaid Man orders a Pipsqueak Patty (a very small version of a Krabby Patty intended for children) for Barnacle Boy at the Krusty Krab, they get into an argument which ultimately results in Barnacle Boy becoming a villain and forming a group called "E.V.I.L." (Every Villain Is Lemons) with Man Ray and the Dirty Bubble. After a protracted fight with Mermaid Man and the "International Justice League of Super Acquaintances (whose costumes and powers are assumed by the main characters of the show), which E.V.I.L. actually wins, he and Mermaid Man patch things up. Barnacle Man, as he likes to be called, gets a little more respect now (even though he mentions that an adult-sized Krabby Patty actually is too big for him).

In the video game Battle for Bikini Bottom, it is revealed that Barnacle Boy has a son, a daughter-in-law, and four "screaming" grandchildren.