Gloomius Maximus is the (former) main antagonist of Rolie Polie Olie: The Great Defender of Fun. He is a gloomy robot from outer space who plans to steal all of the fun from everybody because he never got to have any in his life. He despises birthday parties, as shown when accidentally, an invitation to Zowie's 3rd birthday party was sent to him.
Eventually, after Olie uses a bubble gun of fun on him with a lot of bubbles, Gloomius has a change of heart, and Zowie invites him to her birthday party. He finally gets to have fun for the first time in his life, and then leaves.
He appears in the Baby Bot Chase film as a supporting protagonist.
He was originally voiced by James Woods, and then by the late Paul Haddad onwards.