19. Plácido Domingo (S19 E2 "Homer of Seville")
If you never heard of Plácido Domingo then you have no idea that he is one of the biggest names (if not the biggest) in opera and has been for decades. He was one of the Three Tenors that tore up Concert Halls in the 90's. His appearance was an acknowledgement of how much influence The Simpsons has had in all social classes, from the worst slums in the world to the richest concert halls. In the episode, Homer takes on an opera career (why not?) after it is discovered he can sing, albeit only laying on his back. Who else should he meet but the most popular and sexiest name in opera; Placido Domingo.