While searching YouTube for great bass riffs, I checked the Spencer Davis group's "I'm a Man".
I had never noticed that this bass line is played on an old Kay hollowbody with a thumb pick! I've never seen s thumb pick used in rock before.
GREAT recording of the bass, too...
I can't claim this is one of the great bass riffs, but it's absolutely one of the great rock songs. Turn it up loud and EVERYONE moves.