The Simpsons have had a long line of guest stars, from James Earl Jones to Elizabeth Taylor. For this Sunday night's season finale (May 20th, 2012) on Fox, 8:30 p.m. ET. Lady Gaga goes to Springfield, in "Lisa Goes Gaga". As a long time champion of the socially downcast, she arrives to encourage Lisa to just be herself, and perform for the town...and sing about accepting monsters, among other things.