Phil Lesh (on a good day), though his idiosyncratic style really is different from the "classic" Rock Bass player.
Best rock bass player
Today is the 11th anniversary of John Entwistle's death. I had the pleasure of seeing him play live a few times and was always impressed by his musicality and ability to keep up with Keith Moon- much less lay a foundation for Pete Townshend. I also have always enjoyed Chris Squire, Stanley Clarke, and Flea for similar reasons. Who are some of your favorites?