Definitely one of the greatest bass players that has ever lived. Then again, let's not forget about Percy Jones, Jaco Pastorius, Brian Bromberg, etc...
Do you really need to ask? I mean, c'mon, it's Frank we're talking about here!
I first got wind of this outstanding guitarist through his work with Living Color. But it took his work with Jack DeJohnette on "Music for the Fifth World" to fully grab my attention. Ever since I've been a believer.
Another outstanding guitarist! Known for wearing a KFC bucket on his head, this virtuoso is known for his work with Praxis, Les Claypool, Primus, Bernie Worrel, among many others, before going it alone. While I can't say I like every one of his releases, I like enough to include him in this list.
That's right, Vivaldi! Although his material is of the classical genre, Vivaldi must have been considered a progressive during his time. Possibly the greatest progressive classical composer of all time!