The Simpsons creator Matt Groening confirmed Michael Jackson loaned his voice to Leon Kompowsky, a mental patient who believed he was the King of Pop. The character was encountered by a freshly-institutionalized Homer Simpson in 1991 episode "Stark Raving Dad."
Kompowsky was credited to a "John Jay Smith," muddling Jackson's involvement and leading to debates the character was voiced by an impostor.
"We really did have him," Groening told The Weekly. Approached by Jackson over the phone, Groening initially hung up on Jackson, believing he was on the receiving end of a prank call.
"Because he has a voice that sounds like somebody doing a Michael Jackson bit," he said. "And he said that he loved Bart and wanted to be on the show."
Rumors that the actor behind Kompowsky wasn't actually Jackson persisted for years because of that pseudonym, and Jackson's involvement was muddled further by a birthday song performed for Lisa — "Happy Birthday, Lisa" — that was actually performed by imitator Kipp Lennon.
"He did do the show," Groening said of Jackson. "He didn't want credit for it. It was some kind of deal with his record company or whatever, so when it came time to do the songs, he had a sound-alike singer. And he stood there and watched the guy who was so nervous, who had to sound like Michael Jackson, and [Jackson] giggled."
Clips of Jackson's voiceover role can be seen in the video above.
"Michael Jackson was a fan of the show and wanted to do it and we had to figure a way. It wasn't like your typical 'Michael Jackson?!' where he shows up and does the show for the charity or the fifth grade concert or whatever," Homer Simpson actor Dan Castellaneta says on The Simpsons season 3 DVD commentary (via NME).
"They really figured a great way of having him on the show, so we had a big 300lb white guy who thinks he's Michael Jackson, and Homer meets him and Homer gets committed because he wore a pink shirt to work. It's such an odd show. And the story was great because even though he was this crazy guy who thought he was Michael Jackson, he actually helped Bart write a song for Lisa's birthday. It had warmth, it was absurd, it hit on every level."
Writer and executive producer Al Jean doesn't know why Jackson wished to remain anonymous, hypothesizing, "People thought it'd be slumming to do a cartoon, or an in-joke to do it but not use your name."
"[Writer/producer] Jim [L. Brooks] said: 'After Michael Jackson, that's it, if people wanna do the show we've gotta use their name,' because it was so hard to publicize it without saying it was him," Jean said. "It was just weird."
Jackson wrote the birthday song — aimed at Lisa from big brother Bart's point of view — performed by Bart (Nancy Cartwright) and Lennon as Kompowsky.