Here’s my top 5 Fake Bands of all time (I’m going to pass on Spinal Tap and The Monkees, as IMHO they actually transcended their Fake Band roots and became, to some extent at least, Real Bands)…
5 Neat Guys - clean cut nostalgia act from SCTV. Best song: Who Made the Egg Salad Sandwiches?
N.W.H. - the rap version of Spinal Tap from the movie Fear of a Black Hat. Best song: My Peanuts
Nada - totally cool all girl band from the movie Get Crazy (actually, Lee Ving from Fear sings one of their two songs). Best song: I’m Not Going To Take It
The Dukes of - XTC’s uberpsychedelic alterego. Best song: My Love Explodes
Mayhem - the out of hand punk band from Quincy (I should also give a nod to Pain from C.H.I.P.S.). Best song: Get Up (I Wanna See You Choke)
The Dregs of Humanity, from, I think, an old Jason Bateman sitcom called “It’s Your Move”. The Dregs actually performed on the show, and even gave an interview, but they weren’t real. They were skeletons, “borrowed” from the school science lab, dressed in metal gear, and worked from backstage like puppets.
And there are many (most, probably) of the bands listed in this SNL skit as having songs on the soundtrack for the movie Valentine. My favorites are “Gravel Fork” and “Mr. Hameye”, although “Pi Eating Contest” is pretty good too.
Simon and Milo (if you’re in Canada they’re know as Prozzak. A cartoon band started by two members of the Philosopher King, IIRC)
Josie and the Pussycats
DuJour (from the Josie movie)