Paul Gardner Allen (January 21, 1953 – October 15, 2018) was an American business magnate, computer programmer, researcher, investor, and philanthropist. He was best known for co-founding Microsoft Corporation with childhood friend Bill Gates in 1975, which helped spark the microcomputer revolution of the 1970s and 1980s, later making Microsoft the world's largest personal computer software company. Allen was ranked as the 44th-wealthiest person in the world by "Forbes" in 2018, with an estimated net worth of $20.3 billion at the time of his death.