Jimi Hendrix (RIP)
Eric Clapton
Alex Lifeson
(There are so many. Jimi is a given, but after that you could throw in so many, it's ridiculous. All kinds of cats in multiple genres (I assumed you were talking about Classic Rock/Get the Led Out, Rocktober, etc.)).
EDIT: I was a semi-professional bass player for a while, but I am making my list as a fan, and not a critic.