Robert Fripp
Not a King Crimson fan? Doesn't matter, considering all the different musicians he's collaborated with, chances are good he's appeared on at least one of your favorite albums.
With King Crimson he redefined the idea of what a bandleader could be, he never took the spotlight, he's known for a laid back stage presence, always in the background, sitting on a stool, letting his playing do all the work. It's his guitar playing, which ranged from the subtle to the outrageous that has been the driving force behind the band as it's lineup changed constantly throughout the decades.
He also helped bring to the spotlight many extraordinary musical talents, including Adrian Belew and Tony Levin. Many former members of KC would go on to start their own popular bands, such as ELP, Greenslade, Bad Company, Foreigner and Asia (ok maybe those last three shouldn't be boasted about).
Fripp combined elements of classical music, free jazz, medieval folk, psychedelia, avant garde atonality, ambient soundscapes and the intricate arpeggio oriented sounds of African music and Indonesian gamelan music. All these eclectic influences blended together to create a sound that makes Fripp incomparable to any other guitarist on this planet.
He has been sought after by many great music artists, having played on a variety of albums. Most notably his work with Brian Eno (with whom he developed the innovative Frippertronics tape looping system), but also David Bowie's Heroes and Scary Monsters and Peter Gabriel's first two solo albums. He's also worked with Peter and Michael Giles, Andy Summers, Jazz pianist Keith Tippett, Japan frontman David Sylvian, Talking Heads (on Fear of Music), Blondie, Van Der Graaf Generator, The Orb, Steven Wilson and Porcupine Tree, The Roches, Daryl Hall, California Guitar Trio, G3 (with Steve Vai and Joe Satriani), his wife Toyah Wilcox and a side project called League of Gentlemen which included members of XTC, Gang of Four and Squeeze.
Fripp once described himself as "not a blues guitarist in style, but a blues guitarist in energy and spirit", which is a pretty good description, his influence reaches beyond just prog rock, his use of heavy, distorted riffs and repetition has made it's mark in heavy metal music, and his experimental use of timbres, polyrhythms and alternate tunings has made it's mark on alternative rock and ambient music as well.