I play a variety of instruments; all self taught (save for alto sax), but I think my main inspiration for playing or listening to rock/metal at all is the wonderful outlet it is. There are literally no limits to what you can achieve, and it is my one and only anti-depressant. That said, as far as technique and style goes, my list are as follows:
Bass guitar (my favorite to play): Larry Graham for slap technique, and Flea of RHCP. Meshell Ndegeocello is also a major inspiration as far as "mood" is concerned. I do believe Marcus Miller influenced my love of bass being the "lead" of some tracks.
Rhythm guitar (fun to play): Keith Richards is, of course, going to be on this list. Nasty Suicide purely for providing a "structural" blueprint (for me, at least). Dr. Know of Bad Brains for "style" influences as well as technical aspects.
Lead guitar (new to it): I'm partial to Sabastian Reichl as well as Tosin Abasi; the latter resulting from finally completing a "basic crash course" of how to create and implement progressive harmonics. Paul McGuire has lent a hand for my comprehension of the chromatic scale, and I absolutely adore Adam Dutkiewicz's style. When it comes to lead guitar, my knowledge is very little as it's still quite new to me (in the context of playing.)
Drums (oh, the joy!): My favorite is, and always will be, *drumroll* Louie Bellson. Gotta give credit where credit is due. Notable mentions include Hellhammer (of course), Svein Sander, and much respect to Horde. I have a lot of love towards Norway and it's black metal drummers.
Alto Sax (first instrument I learned how to play): Charlie Parker and David Sanborn. I know they aren't metal, but I draw my art from many different genres and somehow mesh it together to work. You'd be surprised how well a funky sax melody fits with chuggy staccato, mutes, and blast-beats!
You can only take so much from others, though, and realize that inspiration comes from within
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