Fats Waller for swing music
(Ron Thal) Bumblefoot for guitar virtuoso-class
James Hetfield for song writing skills I'm not kidding
Victor Wooten for Bass playing
Kevin Moore for keyboard players - he is a genious to give the vibe you need on a song you have
Louis Armstrong and Dizzy Gillespie for Jazz
I agree with Stoked about popularity and effect on society since the criterias are blurry opening this thread,
Offspring for punkrock they really are great
Kansas for writing Carry on Wayward Son
African American blues roots and gospel music for changing the face of the entire popular culture in a way they probably never imagined
Electric Six for their success at inserting humor into music
Experimental f.ed up rocky music: PRIMUS!
And of course, the person who composed the music for the Dixie Song.