One of the only "supergroups" that ever lived up to that adjective was Fantômas, the avant-metal quartet starring Faith No More and Mr. Bungle's Mike Patton, the Melvins' King Buzzo, Slayer's Dave Lombardo and Mr. Bungle/Secret Chiefs 3's Trevor Dunn.
On 2001's The Director's Cut, they drastically reworked movie scores from a lineup that reads like a Kim's Video Employee Picks section. Some of the most acclaimed movie composers in history get turned into experimetal (sic) freakouts--would you like some grindcore with your "Godfather?" How about Mike Patton's creepiest, child-like singing for "Rosemary's Baby" or "The Night of the Hunter?" Stream it here and see how many of the scores you can recognize--it's about as hard as finding old blues songs in Led Zeppelin II.