In the midst of this most interesting discussion, I'd venture to say that all of the greatest guitarists of all time have been well covered indeed, and well deserve all the lauding heaped upon them here and over the years for giving us great music, great influence, and in general, just a good time musically.  Whereas the obvious has been included, I especially got a charge out of Clipper's reference to (and picture of) Lonnie Mack, one of my early-guitar-days favorites.  For you Heavy Metal people:  Somewhere in the distant past I "read" that Zeppelin was "considered" the first real metal group.  That, of course, could be very subjective. Zep One seems to me to be more metallic and less psychedelic than anything I had heard before it was released.  And recently on a PBS pledge-drive special featuring late 60's groups, a comment was made by a moderator that Steppenwolf's 'Born To Be Wild" tune (released 1968, could not locate the exact release date), contained the first use of the term 'Heavy Metal': "I like smoke & lightning, heavy metal thunder".  That, perhaps, could be a fact, albeit difficult to verify.  Cheers.

the greatest in my opinion is one who no one will ever see anymore, he was murdered on stage in Dec. 04 Darrell Lance Abbott aka. Dimebag Darrell. one of the greatest guitar players of all time.

I think it would be unfair not to mention the Texas Boogie Man Billy Gibbons, aka "Worthless Willie". This thread wouldn't be complete without mentioning him. Maybe not the greatest, but definately a headbanger. Some real bad ass Texas slide. ZZZZZZZZZZZZZ