Nobody comes close to Iommi.

Eddie Van Halen
Wait do I have to post a link for you lazy kids?!!

Wow, there are some amazing links in here. I haven't even heard of a few of these guys...time to find some new songs o_o

Jack White - Ball and Biscuit

@ OP: Agreed, Dave Mustaine in Hangar 18 is one of Megadeths best (all of Megadeth is pretty awesome though)

I actually like Herman li a lot at the moment, people say he is not good because his skill is studio based, but I dsay anyone who can compose those insane riffs is worthy of my respect.

Other favorites are...

Tony Iommi - Black sabbath
Dimebag Darrel - Pantera
Dave mustaine - Megadeth
Martin fieldman - Megadeth
Angus + Malcolm Young - AC/DC
Jimi Page - Led zeppelin
Me
Randy Rhodes - Ozzy osbourne

Hendrix has to be my favourite however I like a lot of the other guitarists from the old rock bands. Paige for example is just fantastic and Clapton is god.

Also Eddie Van Halen's eruption is simply mind blowing the first time you hear it and I love the style of Frusciante.

Since I didn't include with my original post, here is Yngwie Malmsteen - Arpegios From Hell