Jeremy Bentham (1748-1832) was a London based moral, political and legal philosopher. He was predominantly interested in a comprehensive reform of English legal system which was at the time, to put it in his own words, a "nonsense on stilts". Bentham believed that building a good society is an undertaking that should be founded on a verifiable concept of human nature rather than drawn from a jumble of historical prejudices and religious superstitions.  His ambition in ethics was to make it really "scientific" and "empirical" as opposed to metaphysical doctrines devoid of any real content. This project was in conformity with the accepted view of the time that all theory must be grounded in empirical facts. The first step in that endeavor was to recognize the true motivating forces of human conduct – pleasure and pain. Instead of preaching abstract moral values ethics should articulate what people really want and anyway tend to do. 

Roger Crisp gives a full and detailed background to Bentham, here.

The Internet Encylopaedia of Philosophy has a brilliant article on Bentham and his philosophy, well worth reading, here.