Known as Blind Owl due to his poor sight, he was in many ways the heart of the sound behind Canned Heat. His guitar playing was a major influence to many with his use of altered tunings.
Al Wilson was also instrumental in the discovery/rediscovery of Son House and John Lee Hooker in the 1960's. Even to the extent he taught Son House how to play the songs 'House' had recorded in 1930 and 1942 and which he had forgotten over a long absence from music.
Here's a very rare bit of film of him with Canned Heat at Montreux in 1970.
Indeed this white man really could sing the blues..
There's a tribute website to Al that's well worth a look : alanwilsoncannedheat.com