
Yes it's true.The bold man in this pic is voiced by Michael Jackson in the episode "Stark Raving Dad"
The Michael Jackson Guest Appearance
Michael Jackson voices Leon Kompowsky when he is talking, and a Michael Jackson impersonator performs all singing parts for this character. Jackson's guest appearance is credited to John Jay Smith. The DVD commentary for this episode indicates that Jackson approached the Simpsons camp wanting to appear on the show, but due to a contract obligation, was not allowed to sing. However, he did write "Happy Birthday Lisa" for the show. Great secrecy surrounded the guest appearance for some time, and even Matt Groening when appearing on the the Jay Leno show, did not openly reveal that it was Jackson, although he hinted strongly. It wasn't until the episode Itchy & Scratchy: The Movie that a more open clue was given to viewers, when Lisa mentions that Dustin Hoffman and Michael Jackson made cameo appearances in the movie, stating, "They didn't use their real names, but you could tell it was them..." (Dustin Hoffman, of course, voiced Mr. Bergstrom, in the episode Lisa's Substitute, and his guest appearance was similarly shrouded).from Simpsons Wiki ^^
