Robert Williams (born 1943) is an American Artist who paints insane, hallucinogenic art with a strong emphasis on American Pop Culture. (I give up, he is beyond description, ok?). He was part of the Zap Comix collective of artists which included R. Crumb, Rick Griffin, Gilbert Shelton & other notables.
(I noticed recently that his work fits neatly with my love of film posters which I collect.)
Oh yeah, dude’s really into Hot Rods also: