“Simpsons” creator Matt Groening was doing an interview in Australia when he cleared up a fan rumorthat has been circulating for 27 years: Leon Kompowsky is Michael Jackson. Michael ended up voicing the character, who was a psychiatric patient convinced he is Michael Jackson. Apparently, it was Michael’s idea. Jackson called him to volunteer for a cameo. Groening says he initially hung up on Jackson because he thought someone was pranking him. After the King of Pop called back, Matt says he was convinced. Matt put him in the 1991 episode “Stark Raving Dad.” They credited the voice of the character to “John Jay Smith” instead of Jackson. The singing voice was an actual impersonator because Michael’s record company had the rights to his singing voice.