Bartman

Bartman is Bart's alter ego.

Appearance
In Three Men and a Comic Book Bartman was just Bart with a purple bandana on his head. However in Revenge is a Dish Best Served Three Times he was Bart with a complete Bartman outfit with equipment.

Bartman Begins
After leaving the Gotham City Opera House, Homer and Marge are killed by Snake Jailbird in a dark alley. Homer pleads Bart to avenge him. Bart does as his father says and swears revenge on Snake, giving birth to his superhero ego, Bartman with the help of his grandpa. He flies around Gotham City, defeating enemies on his way for justice. When Serpent, Snake's alter ego, attempts to steal the "Stealable Jewels of the Orient" from the Gotham Natural History Museum, Bartman arrives, saves the Jewels, and kills Serpent by impaling him on the fangs of a snake statue. In the end, a reporter (played by Lisa), reminds Bartman that the Serpent's death will not revive his parents. Bartman agrees, but adds that he now feels better, plus he got zillions of dollars and no parents to tell him what to do.

The Real Story
In The Bartman comics, Bartman fights bullies and super villians who pop up in Springfield. This series ran for 6 issues in the 90s, but Bartman still frequently appears in the Simpsons Comic Universe.

The Simpsons Game
Bart can transform into Bartman.