Tie: 1. Michael Jackson- (S3 E1 "Stark Raving Dad") and Aerosmith (S3 E10 "Flaming Moe's")
When Season 3 hit, it hit hard. With two relatively successful seasons under their belts, the show was breaking ground in adult-oriented prime time cartoons and to cap it off, they reined in the two biggest acts of the day; Michael Jackson and Aerosmith. Michael Jackson's story of appearing on the Simpsons makes for an interesting legal read itself. Highlights include; a pseudonym for appearing (John Jay Smith), and the producers not being able to confirm that he was the guest star before or after airing, he would not actually sing (instead done by Jackson impersonator Kipp Lennon) although he was the one to suggest that he and Bart write a song together (Happy birthday Lisa). Jackson also penned the campy 90's novelty tune 'Do the Bartman' uncredited.
With that quasi-controversy in the air, a couple months later the real hammer dropped and the first of what is an ongoing list of guest bands appeared in the form of already aging at that time Boston rockers, Aerosmith. They were riding the high of being the Kings of the rock and roll pile after a 20 year absence with their 10th studio album Pump, which went to #5 in the US and #3 in the UK and like Jackson were big fans of the show and so they had their people contact the Simpsons people about making an appearance, which was also to become a large trend. By getting the two biggest acts in music at the time and the resulting world-wide publicity it generated in what was only the third season of the show's existence it cemented the age of a new tradition, where bands and people could cross-promote themselves in not only the real world but in an animated one as well. And while some other shows have attempted the feat none have been able to replicate it, for as Professor Mayhem discovered - 'The Simpsons Already Did It'. So that's 20 of the best musical acts to appear on The Simpsons. Feel free to add any omissions and reasons in the comments section below.