Archimedes of Syracuse

Archimedes of Syracuse (287 BC - 212 BC) was the greatest mathematician of his age. His contributions in geometry revolutionised the subject and his methods anticipated the integral calculus 2,000 years before Newton and Leibniz. He was also a thoroughly practical man who invented a wide variety of machines including pulleys and the Archimidean screw pumping device.

There's a very insightful NOVA special on his life called Infinite Secrets which I bought from Amazon.com. You can also view it free on youtube.