Dave Allen - not just because he was a comedian, but because he took his material from everyday life, it was original and at times almost unbelievable.
Ah what an inspiring question !
Frank Zappa - because he told it like it was and delivered serious messages through (excellent) music in a uniquely witty and humerous manner.
(Also agree with Mojo Jo Jo Jo Jo!)
Sorry mojo and AP who is Bill Hicks? I agree with jamesnan about Tommy Cooper - he only had to amble on the stage to get me laughing and his humour was always clean - no mucky stuff.