Green Jellÿ (, green Jell-O) is an American comedy rock band formed in 1981. Originally named Green Jellö, the band changed its name due to legal pressure from Kraft Foods Inc., the owners of the Jell-O brand, who claimed that it was an infringement of their trademark.

Known for sophomoric humor, theatrical performances, and intentionally crude musicianship, Green Jellÿ has had hundreds of members during its existence, with vocalist Bill Manspeaker the only consistent member throughout. Notable past members include Danny Carey and Maynard James Keenan, who were both in Green Jellÿ during the early 1990s and went on to form Tool.

To date, the band has released five studio albums: Triple Live Möther Gööse at Budokan (1989), Cereal Killer Soundtrack (1993), 333 (1994), Musick to Insult Your Intelligence By (2009), and Garbage Band Kids (2021). They are best known for their 1992 hit "Three Little Pigs", which was adapted from the fairy tale.