Just from the Grateful Dead alone: Ron "Pigpen" McKernan, Keith Godchaux, Brent Mydland, Vince Welnick, and of course Jerry Garcia. A few others that haven't been mentioned yet: Duane Allman, Berry Oakley, most of the members of the classic lineup of Lynyrd Skynyrd, Clarence White, Merle Watson, Michael Hedges...will probably add more as I think of them...