Portland Trail Blazers owner Paul Allen died Monday from complications from non-Hodgkin's lymphoma, his family said Monday.

Microsoft's co-founder, Allen battled cancer three times -- most recently disclosing October 1 that his non-Hodgkin's lymphoma had returned. He also owned the Seattle Seahawks and actively promoted brain research and his company, Vulcan, is a major Seattle real estate firm.

Forbes values his fortune at $20.3 billion, making him the world's 21st richest person. The magazine tallies his total philanthropic contributions at $2 billion, including $500 million to the Allen Institute for Brain Science and contributions to address ocean health and homelessness. He was also an avid supporter of the Oregon Shakespeare Festival in Ashland.

"My brother was a remarkable individual on every level. While most knew Paul Allen as a technologist and philanthropist, for us he was a much loved brother and uncle, and an exceptional friend," Allen's sister, Jody Allen, said in a written statement.

"Paul's family and friends were blessed to experience his wit, warmth, his generosity and deep concern," she wrote. "For all the demands on his schedule, there was always time for family and friends. At this time of loss and grief for us – and so many others – we are profoundly grateful for the care and concern he demonstrated every day."

A Seattle native, he befriended his Microsoft co-founder Bill Gates in school and they both became computer programmers. Allen attended Washington State University but, like Gates, he dropped out of college to work in computing.

The pair started Microsoft in 1975, while working in New Mexico. IBM subsequently chose Microsoft to provide the operating system for its first personal computers, an enormous break that opened the door for Microsoft to become one of the world's biggest companies.

He left the company seven years later, shortly after being diagnosed with lymphoma -- his first cancer diagnosis. Allen wrote later that he experienced the first symptoms while attending the Oregon Shakespeare Festival in Ashland.

"Paul and his family have been coming to OSF for decades, and Paul's love of and support for the Festival has been essential to the art and community we create here," the Oregon Shakespeare Festival said in a written statement Monday. "He had a particular, inspiring passion for making art and the classics relevant to young audiences. Just last night we performed in the space that bears his family name – the Allen Elizabethan Theatre – for the final time this season. Our hearts go out to the Allen family."

-- Mike Rogoway