Paul Allen, who with Bill Gates founded Microsoft, has died at the age of 65. His death comes shortly after he resumed treatment for non-Hodgkin's lymphoma; the cancer had returned after being in remission for nine years.

Allen was a Seattle native and went to high school with Gates. The two kept in touch at university—Allen at Washington State, Gates at Harvard—and when Allen dropped out in 1975 to start a company to develop software for the MITS Altair 8800, he soon convinced Gates to follow. That company was Micro-Soft, which shed its hyphen the following year. In 1980, Microsoft was chosen by IBM to develop DOS for its new PC. With the success of the PC and PC compatibles, Microsoft became hugely successful.

Allen had his first run-in with cancer in 1982, when he was diagnosed with Hodgkins lymphoma and drastically cut back his work at the company while recovering. He formally left Microsoft in 1983, but he retained his share of ownership and became a billionaire when the company went public in 1986.

With this newfound wealth he created his own investment firm, Vulcan Inc. One funding priority has been space; he helped fund the Allen Telescope Array in California, and in 2011 he created Stratolaunch, a space company that wants to launch rockets from a giant airplane. Local sports were also a priority; Allen bought the Seattle Seahawks NFL team in 1996 to prevent it from being moved to California, and he was a minority owner of the Seattle Sounders MLS team.

Beyond this, he invested hundreds of millions of dollars to research disease, artificial intelligence, and bioscience. He also contributed substantial funding to organizations working to fight the 2013-2016 Ebola epidemic in West Africa. He established the Museum of Pop Culture in Seattle, along with a number of other institutions, to showcase his collection of art, aircraft, computers, and memorabilia.

When not working, Allen was by all accounts a talented guitarist and released a blues rock album in 2013. He also had an interest in undersea exploration and was involved in locating a number of lost planes and ships.

Allen never married and had no children.

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