Mermaid Man and Barnacle Boy are a duo of fictional characters from the American animated television series, SpongeBob SquarePants. They were respectively voiced by guest stars Ernest Borgnine and Tim Conway, who both previously starred in the 1960s sitcom McHale's Navy. Mermaid Man and Barnacle Boy first appeared in the eponymous season one episode that premiered on August 21, 1999, and have since been featured as recurring characters. Following the actors' deaths, the characters have been relegated to non-speaking cameos after creator Stephen Hillenburg requested not to recast the characters.

SpongeBob SquarePants is an American animated television series created by marine science educator and animator Stephen Hillenburg that aired on Nickelodeon as a sneak peek after the 1999 Kids' Choice Awards on May 1, 1999, and officially premiered on July 17, 1999. It chronicles the adventures of the title character and his aquatic friends in the underwater city of Bikini Bottom. The series received worldwide critical acclaim, and has gained popularity by its second season. As of 2019, the series is the fifth-longest-running American animated series. Its popularity made it a multimedia franchise, the highest rated Nickelodeon series, and the most profitable intellectual property for Paramount Consumer Products. By 2019, it had generated over $13 billion in merchandising revenue.