Paul Allen, the billionaire co-founder of Microsoft, died on Monday. He was an investor, entrepreneur and philanthropist who influenced many aspects of modern life — from technology and science, to sports and music.

Allen was 65, his investment firm Vulcan said in a statement announcing his death. He died in Seattle from complications related to non-Hodgkin’s lymphoma two weeks after Allen said he was being treated for the disease.

Non-Hodgkin’s lymphoma, like the less-common Hodgkin’s disease, is a cancer of the lymphatic system.

“My brother was a remarkable individual on every level,” Allen’s sister, Jody Allen, said in a statement on behalf of his family. “He was a much loved brother and uncle, and an exceptional friend.”

Allen founded Microsoft (MSFT) with Bill Gates in 1975, several years after the two met as fellow students at a private school in Seattle. Allen left the company in 1982 after he was diagnosed with Hodgkin’s disease.

“I am heartbroken by the passing of one of my oldest and dearest friends, Paul Allen,” Microsoft founder Bill Gates said in a statement on Monday. “Paul was a true partner and dear friend. Personal computing would not have existed without him.”

Microsoft CEO Satya Nadella called Allen’s contributions “indispensable.”

“As co-founder of Microsoft, in his own quiet and persistent way, he created magical products, experiences and institutions, and in doing so, he changed the world,” Nadella added.

Allen didn’t slow down after leaving Microsoft. He stayed on the company’s board of directors for several years while establishing his own philanthropic foundation, along with Vulcan, his investment firm.

He bought two professional sports teams: the NBA’s Portland Trail Blazers and the NFL’s Seattle Seahawks. He was involved with both until his death.

Friends, family and other admirers also praised Allen for his significant philanthropic contributions.

The technologist, who Forbes says was worth $20.3 billion at the time of his death, donated more than $2 billion to charity. He also founded several organizations, including the space transportation company Stratolaunch, the Allen Institute for Artificial Intelligence and another Allen Institute that focuses on bioscience. Vulcan, which he founded, managed his business and philanthropic interests.

In his later years, Paul Allen took up a number of other projects -— from the charitable to the adventurous.

In 2014, he pledged at least $100 million to help fight the Ebola virus. In 2017, he pledged $30 million to house Seattle’s homeless.

Allen was still finding other ways to leave his mark on the world this year. A team of explorers led by him discovered wreckage in March from the USS Juneau, a World War II cruiser sunk by a Japanese torpedo in 1942.

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