Paul Allen (January 21, 1953 – October 15, 2018) was an American entrepreneur, investor, and philanthropist best known as the co-founder of Microsoft Corporation. Born in Seattle, Washington, Allen met Bill Gates while attending Lakeside School, and their shared interest in computers led to a lifelong partnership. In 1975, Allen and Gates founded Microsoft, initially focusing on developing software for the emerging personal computer market. Allen played a central technical role, notably helping to secure the contract to adapt BASIC for the Altair 8800 and later negotiating the deal for Microsoft to license the operating system that became MS-DOS to IBM. This partnership positioned Microsoft at the forefront of the PC revolution. Allen served as Microsoft’s chief technologist until 1983, when he stepped down due to a diagnosis of Hodgkin’s disease. He remained on the company’s board of directors until 2000. After leaving Microsoft, Allen founded Vulcan Inc., a private investment and project management company, to oversee his diverse business interests. He became a major owner of professional sports teams, including the Seattle Seahawks (NFL) and the Portland Trail Blazers (NBA), and invested in technology, media, and real estate ventures. Allen was also a significant philanthropist, co-founding the Paul G. Allen Family Foundation and funding major initiatives in science, education, and the arts. He contributed $100 million to establish the Allen Institute for Brain Science, supporting open-access neuroscience research. Allen’s legacy includes pioneering work in technology, substantial contributions to philanthropy, and lasting impacts on sports and culture in the Pacific Northwest. He passed away in 2018, but his influence continues through the organizations and projects he supported.