Paul Gardner Allen (January 21, 1953 – October 15, 2018) was an American business magnate, computer programmer, researcher, investor, and philanthropist. He co-founded Microsoft Corporation with childhood friend Bill Gates in 1975, which helped spark the microcomputer revolution of the 1970s and 1980s. Microsoft became the world's largest personal computer software company.[1] 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.[2][3]