My list is miles long, but here are the ones that come to mind.

Readying myself for the coming firestorm...

Stevie Ray Vaughn
Iron Maiden
Yngwie Malmsteen

And possibly more understandable to some:

Slipknot
Captain Beefheart
Ponytail
Sun Ra Arkestra

Honestly, I just never quite got any of these groups. That's not to say that I won't eventually, or that they have no redeeming qualities, but they just all seem not to click with me for whatever reason.