American software programmer and philanthropist Paul Allen was BOTD in 1953. Born in Seattle, Washington, he attended a private school in Seattle where he met friend and future business partner Bill Gates. He studied at Washington State University, dropping out after two years to work as a computer programmer. In 1975, he and Gates founded Microsoft Corporation, winning a contract with IBM to develop a disk operating system for IBM’s original personal computer. After frequent disputes with Gates and a cancer diagnosis, he left Microsoft in 1983, retaining his company shares despite a buy-out offer from Gates. Both became billionaires when Microsoft was listed on the stock exchange in 1986. He co-founded Vulcan, a philanthropic organisation to manage his business and philanthropic efforts, donating more than US$2 billion to educational, health and arts charities. He also established enterprises to research brain science, artificial intelligence and space travel. Allen never married or had children, generating speculation about his sexuality. In the 1990s, he purchased gay actor Rock Hudson’s Los Angeles home, and made a US$65 million donation to AIDS research. He died in 2018, aged 65, with an estimated fortune of US$20.3 billion.