Over the years, (thanks in part to Comic Book Guy) there have been countless references to superheroes on The Simpsons. But on the rare occasion, the show has actually featured some superheroes of its own creation. Here is the rundown.
Radioactive Man, known for his catch phrase "Up and atom!" first appeared in the first season episode, "The Telltale Head." He was a fictional comic book character beloved by young Bart. He was featured in the seventh season episode "Radioactive Man" in which a movie based on the character was being filmed in Springfield. Milhouse was cast as the sidekick Fallout Boy.
Bartman, the alter-ego of Bart Simpson first appeared in the third season episode, "Three Man and a Comic Book."
The character returned in the 18th season episode "Revenge is a Dish Best Served Three Times" in a segment called Bartman Begins- an obvious play on Batman Begins. This incarnation of Bartman existed outside of the shows normal continuity.
In season 11's "Treehouse of Horror X," Stretch Dude and Clobber Girl teamed to save Xena.
Poor Xena had been captured and stored in a Mylar bag by the diabolical Collector.
In season 13's "I am Furious Yellow," through a series of planned traps, an enraged Homer was transformed into a walking Hulk homage.
In season 15's, "Simple Simpson," Homer donned his own disguise as Pie Man with Bart sidekicking as the Cupcake Kid.
The same episode opened with a Batman themed couch gag set in the "Simpson-Cave."
Season 21 opened with, "Homer the Whopper,"
In the episode, Comic Book Guy invented a character named Everyman AKA Avery Mann, who could absorb the powers of any comic book character (ie Iron and Plastic Men). Homer was eventually cast in a film adaptation of the comic.