Five of the best:
#4 Steve Clark. Before his untimely passing in 1991, Steve was the man who made sure Def Leppard never strayed too far from their hard rock roots; it's doubtful that X would have surfaced if he'd been around to have a say in the matter. With his low-slung Les Paul and exaggerated shape-throwing, Steve was always twice as cool as anyone else in Def Leppard could ever be. His off-the-cuff approach and hard riffing had more to do with Jimmy Page than Mutt Lange. The drawn-out Hysteria sessions and resulting super-slick album were not really the Clark style. Never a technical player, he had a combination of melody, feel, and classic rock cool, sloppy blues-rock licks that blew mindless widdling out of the water. Steve shines on pre-Hysteria Def Leppard albums and the B-side collection Retroactive. Defining moment: "Bringin' on the Heartbreak/ Switch 625" from High 'n' Dry, 1981.
Another Steve Clark mention in this article come under the paragraph about Slash:
Cool he [Slash] may be, but a great guitarist he ain't. He desperately wants to be Jimmy Page and Joe Perry, but Steve Clark is the true spiritual successor of those guys, not Slash.