25Tony Iommi

Ebet Roberts/RedfernsI remember the first time I heardBlack Sabbath. My older brother got their albumMaster of Realityfrom a kid who lived next door, and we'd been passing it around like it was crack. We were playing it with the lights down and a candle burning, when my dad burst into the room. He was like, "What is this shit?" Then he broke the record right in front of us. But the music had just struck me like lightning. I truly enter the Iommi-sphere every time I put a guitar on. Tony is a metal pioneer, but there's a real finesse to his playing; it's not all that fast. His phrasing has such a classic vibe, and I draw a lot of inspiration from Tony's trilling.I injured myself at a Black Sabbath reunion concert in 1999. During "Snowblind," we were all holding each other, and then we fell over and I hit a chair and broke my ribs. I was like, "Fuck, it hurts so bad, but I don't want to leave. I have to keep watching Tony play!" By Brent Hinds of MastodonKey Tracks:"Iron Man," "Sabbra Cadabra," "Children of the Grave"

26Brian May

Phil Dent/RedfernsProbably the only guitarist to get a degree in astrophysics,Queen's lead guitarist (and frequent songwriter) is a brainy adventurer who's always seeking new effects. An early goal of his was "to be the first to put proper three-part [guitar] harmonies onto a record" like the orchestrated squeals of his solo in "Killer Queen." Brian May layered dozens of guitar parts onto individual tracks, building palatial walls of sound. Appropriately, even his instrument sprang from his imagination: His main guitar, the Red Special, a.k.a. the Old Lady, is a homemade wonder, constructed by May and his father in the early Sixties out of components including wood from a fireplace (he has been known to play it with a sixpence coin rather than a pick). It's yielded everything from the pirouetting, trebly solo in "Bohemian Rhapsody" to the proto-metal riffing of "Stone Cold Crazy." "I can listen to any player and pantomime their sound," Steve Vai said, "but I can't do Brian May. He's just walking on higher ground."Key Tracks:"Keep Yourself Alive," "Brighton Rock"

27Bo Diddley

Robert Altman/Michael Ochs Archives/Getty Images"It's the mother of riffs," says guitarist Johnny Marr: the "Bo Diddleybeat," introduced by the Chicago guitarist born Ellas Otha Bates, a.k.a. Diddley. Driven by his tremoloed guitar, songs such as "Mona" and "Bo Diddley" unleashed a superpowered version of a West African groove that was handed down by slaves; after Diddley, the riff would be hijacked by everyone fromBuddy Hollyto theRolling Stones(who covered "Mona" in 1964), and, later, garage rockers and punks, who responded to its raw simplicity. (The Clashmade the connection formal when they brought him on tour in 1979; theSmithsbuilt "How Soon Is Now?" around the riff.) "Anybody who picked up the guitar could do it," says Dan Auerbach of the Black Keys. "If you could keep a beat, you could play Bo Diddley." "His style was outrageous,"Keith Richardssaid; it suggested "that the kind of music we loved didn't just come from Mississippi. It was coming from somewhere else."Key Tracks:"Bo Diddley," "Road Runner," "Who Do You Love?"

28Johnny Ramone

Michael Ochs Archives/Getty ImagesThe father of punk-rock guitar and a huge influence on riff-driven modern metal, Johnny Ramone is one of the instrument's great anti-heroes. John Cummings made his name with an inexpensive Mosrite guitar, on which he hammered out high-speed downstroked barre chords in a slashing, minimalist style that appropriately became known as "buzzsaw." A pure rhythm engine,Ramonealmost never played a solo, but his playing had the headlong surge of an oncoming subway train. In an era when "heavy" was synonymous with "slow," the primitive, metronomic swing of his riffs on "Blitzkrieg Bop" and "Judy Is a Punk" and the trampoline-pop grind of "Rockaway Beach" showed you could speed things up without losing an ounce of power (somewhat surprisingly, his own guitar hero was Jimmy Page). "Johnny was the first guitar player I ever saw play like he was really mad," testified Henry Rollins. "And I was like, 'Damn. That's cool.'"Key Tracks:"Blitzkrieg Bop," "Judy Is a Punk," "Rockaway Beach"