I’d go with Sammy Hagar; his lead duels with Gary Pihl in his solo work are brilliant. He was overshadowed by Ronnie Montrose and Eddie Van Halen in his other bands, but he’s no slouch.
Gotta agree with Derek Trucks. Really amazing and he’s so young.
Robbie Robertson was a great guitarist, though he hasn’t done much noteworthy since his days with The Band.
How about the late Brian Jones of The Rolling Stones?
Scott Gorham from Thin Lizzy. Fantastic guitarist all by himself, simply amazing when paired up with Gary Moore.
Obviously, I agree with you(link to a thread I started entitled Slide Guitar: A Lesson on How it’s Done). But Trucks isn’t underrated - he’s practically viewed as the Second Coming (of Duane Allman, at least, if not Slide Guitar Jesus) ;).
I am thinking about someone who is famous / songs still get played but who doesn’t get the gunslinger credit that perhaps they deserve…Trucks is a total gunslinger and is respected highly for it. Townshend, Richards, Ramone and Young’s material gets played all the time - as does Tommy Iommi’s - and it is totally guitar driven - but you don’t hear them get mentioned often in the Respected Guitar God Sweepstakes.
Along those lines - even though I am not a fan of their music - I have to assume Mick Mars of Motley Crue is pretty solid as a guitarist. Very weird to have such a guitar-driven sound and have him buried in the back row behind Nikki, Tommy and Vince as “personalities” - I know he’s weird looking and has some form of joint disease, so that has to be part of it…
Steve Hackett did some awesome guitar work with Genesis and on a number of solo albums after he left the band. Although, I have to admit, I have no idea what the guy’s been doing for the last twenty years or so.
I dunno. I’ve fallen out of my musician circles for the most part. My subscriptions to the guitar mags lapsed many years ago. (Only recently did a friend in ad sales hook me up with a comp subscription.) Maybe the guitarist community does think he’s the second coming. But when I mention Derek Trucks to my non-musician friends, most of them have no idea who he is. Granted, most of my friends are out-of-touch 30-somethings who start rocking out whenever a Bon Jovi song comes on the jukebox (GROAN!), but I suppose “underrated” depends greatly on your point of view.
Agreed on Derek Trucks, but I can’t agree with you here. To me, there’s ample reason why Mars was buried behind the other personalities in Motley Crue. His playing lacks soul. I always got the impression he was emphasizing playing fast over playing with feeling. YMMV.
For all I know he’s a god among guitarist circles, but I was thinking recently that Waddy Wachtel deserves to be more of a household name. A couple of Warren Zevon’s songs came on my iPod the other day, and I kept repeating thm over and over just to listen to Wachtel’s guitar (particularly “Poor Poor Pitiful Me”).
Holdsworth is awesome. I first heard him with UK then with a couple of Bruford albums from the late 70s. He turned out to be more of a fusion guy and got lost in that syn-tar thing, but definitely made his presence known with some rock-ish projects early on. I saw him at a club in Denver in the '80s touring with Chad Wackerman and Jimmy Johnson and Paul Williams. There were maybe a few dozen people there, unfortunately. I downloaded a more recent live recording from iTunes and it’s pretty much the same thing. They play to a smattering of applause and a few whoops from the die-hards.
A couple of my unsung favorites are Dominic Miller - Sting’s guitarist, and David Rhodes, who’s been playing with Peter Gabriel since forever.
I hear you - but I am inclined to attribute that to the current state of music. As we’ve discussed hear on the 'Dope, music isn’t the crossover force it once was - it is not the symbol of the Generation Gap, the thing that kids and parents can’t agree on and that the kids use to stake their own claim/voice. That’s now the Internet and specific social networking sites, IMHO…so I doubt any player can achieve the crossover god-hood of a Clapton or a Hendrix.
My M definitely doesn’t V from yours - I am not a fan (okay - I dig the riff off Looks That Kill and the chorus from Kickstart My Heart, but that’s all I’ve got). I was just pointing out that the Crue have endured, their songs get played a lot on rock radio and are very guitar driven.
So - when can I check out the Brian Moore’s? 
I’ve actually never played one, but of course have heard good things.
Mick Jones
Dude - which one? The one from the Clash is a great, distinctive and yeah, underrated guitarist and songwriter. Strummer typically got all the cred, but Jones is a great player.
As for the one from Spooky Tooth and then Foreigner - you know what? For a classic rock, in-the-pocket player, he does fine. I will never hold Juke Box Hero up against anything truly good, but he has a great 70’s classic rock tone and the playing serves the songs really well…
Maybe not as underrated as the others here, but Dicky Betts seems to be seen as “the other guy” to Duane Allman, even though he really contributed far more to the band.
Yeah, but only among people who’ve heard of him. 
That’s a relatively small portion of the listening public, I think. I do think of Trucks as underrated, and the same goes for Duane Allman, who had an even shorter career than Hendrix, much less than the very famous players like Clapton and Page.
For whatever it’s worth I can’t really imagine Townshend and Keef as underrated, but maybe I’m thinking of their fame rather than their esteem.
That was the reason for the !
(For the record, Mick Jones of The Clash.)
Buck Dharma from Blue Oyster Cult. He has an unmistakeable sound, and I love the way he plays around with the themes of the songs he’s soloing in.
Harvester of Eyes - a weird and not incredibly inspiring song, but listen to how he messes with the rhythm at 1:26, and then just blasts the tune open beginning at 1:40, then comes back in with a complete reinterpretation 3:36. I think he’s an extraordinarily gifted musician, breaking out of the strictures of Texas Boogie/Blues scales and rhythm.
Longer, live solo. Also, his guitar is made of Swiss cheese.
I sometimes think I can hear people soloing who have been influenced by him - in particular Third Eye Blind and even The Hold Steady, but I’ve never heard him referenced by any guitarist.
I don’t think the late Rory Gallagher is exactly the household name I think he should be, at least not in the US; don’t know about elsewhere. I don’t know if that qualifies him for being underrated, though, as the people who remember him know he was a hell of a player.
WordMan, I’m so glad you linked to that. I just listened to “Down in the Flood,” added it to my Amazon wish list, and if the rest of the CD sounds like a winner, it’s on my short list for my gift card.
I’ve got more Crue buried in the deep recesses of my iPod than I’d prefer that people know. That said, I find most of it completely unlistenable these days. Even so, I’d probably go to a Crue show if someone gave me free tix. 
I love them. If you ever make it out to Holtsville, Long Island, do drop by and I’ll bring up the C-90P and let you have at it.
Several years ago, I was faced with the same problem a lot of guitarists are faced with as they enter their 30s without having “made it.” I had to take a lot of Strats, Les Pauls and other wonderful guitars and consolidate the ol’ collection by selling. So I went from having around two dozen pieces to having five. I have three Brian Moore custom shop jobbies (C-90, C-90P and C-55), an EBMM Eddie Van Halen model I couldn’t part with (rare trans. black color) and a Martin single cutaway electric/acoustic. I also kept a Warwick bass for home recording. The Strats, Les Pauls, Kramers from the hair band days, etc. all went home with new owners. 