Paul Erdős

Among the most prolific mathematicians in history, he published roughly 1,500 papers, many written with the more than 500 collaborators he accumulated through a nomadic lifestyle devoted entirely to mathematics, arriving at a colleague's door and moving on once a proof was finished. His work in Ramsey theory, number theory and combinatorics was extensive enough to spawn its own metric, the Erdos number, measuring collaborative distance from him; he died, fittingly, at a mathematics conference in Warsaw in 1996.