Define "rock" and define "band".
Bruce Springsteen and the E-Street Band
Creedence Clearwater Revival
Is Billy Joel a rock band?
Ben Folds Five
Is Elton John a rock band? I could put The Beatles, Tom Petty and the Heartbreakers, Meat Loaf, Queen, Styx, Herman's Hermits, The Proclaimers, and Kansas up there pretty high.
Other than Springsteen, though, I'm not really loyal to bands. Springsteen is probably the only group for which I have all of their mainstream releases.