Interesting.
For comedy,
Spike Milligan - I think he was an asset to British humour, Matt mentioned John Cleese, John Cleese was very good for British job, but I think he got some of his inspiration from Spike Milligan, certainly Monty Python did.
I'd like to say Shakespeare, but I'm doing a project on somebody who influenced so much in our literature, without us even recognising it and even Chaucer and Shakespeare took some ideas from this fellow and that's
Ovid. It seems that he defined (from the Greek mythology) most of the archetypes in literature.
Matt Stone and Trey Parker. I'm sure this one will bring about some puzzled looks, particularly from those who do not find their humour funny, but I think these guys have really push the boundaries of satire in terms of what can be said, they really don't discriminate when they choose who to mock, yet they can do it in a way that is not directly offensive (though someone's always going to be offended)
Stephen Hawking. He's managed to do a lot for the world of science and making quatum phyics understandable to thickos like myself. I'm going to have to agree with others on him.
Eintstein. Does it really need to be said? Look at the technology we've developed because of him.
Immanel Kant. A real benefit to logic, reason and philosophy, I think he redefined some of the ways we've thought about things. His 'Critique of Pure Reason' has been a real contribution.
Sigmund Freud. Sometimes he could have been one of his own patients, but an asset to psychology, therapy and metal health, so of the things he said were true and got the world of psychology thinking along the right lines. We can eiter ignore or laugh about the Oedipus Complex, except perhaps when it's relevant.
Bill Gates and Steve Jobs. Lets not forget both of them, in a way they've scratched each other's backs despite being rivals, by stealing each other's ideas and their companies working hard, computers and operating systems have really developed well.
Others I'd name are stepping into what you don't want posted.