"Fat" is a song by "Weird Al" Yankovic. It is a parody of "Bad" by Michael Jackson. It is the second parody Yankovic did of a Jackson song, the first being "Eat It", a parody of Jackson's "Beat It". "Fat" is the first song on Yankovic's Even Worse album.

Nowadays, when the song is performed in concert, Yankovic wears a fat suit and a mask that makes his face appear fat. Though he has undergone laser vision correction surgery, he wears glasses for this song, which are needed to hold the mask on. Since he no longer needs to use actual glasses, the lenses on the mask have since been changed to clear plastic.