Clarence White is probably the most under-rated guitarist of all time, but one of the most influential. Few guitar players have had the influence across multiple genre's that Clarence had. He was an important figure in the development of bluegrass, country, country-rock, and rock guitar styles.
Clarence White and Gene Parsons invented the b-string bender... which would go on to be used by artists such as Jimmy Page on 'All of my love' and 'Ten Years Gone'. Mike Campbell (Tom Petty and the Heartbreakers), Pete Townshend (the Who), Bernie Leadon (Eagles), Albert Lee, Peter Buck (R.E.M.) and Rich Robinson (Black Crowes).
Clarence playing the 1st B-bender with The Byrds in 1968.
Here is Tony Rice, absolutely killing it solo, playing his 1935 D-28 that was formerly owned by Clarence White.