Microsoft co-founder Paul G. Allen died Monday in Seattle following complications of non-Hodgkin’s lymphoma, according to a statement issued by his family and business partners.

Allen was 65 years old.

In 1975, Allen and Bill Gates co-founded Microsoft, helping to usher in what would become a revolution in software and personal computers.

Allen left the company in 1982, turning his attention — and enormous wealth — toward a range of interests. He owned organizations focused on sports (Seattle Seahawks and Portland Trailblazers), entertainment (Cinerama, Museum of Pop Culture, and the Upstream Music Fest), history (Living Computers: Museum and Labs and the Flying Heritage & Combat Armor Museum), technology (Allen Institute for Artificial Intelligence and Stratolaunch), and property development (Vulcan Capital and Vulcan Real Estate).

“Today, we mourn our boss, mentor, and friend whose 65 years were too short — and acknowledge the honor it has been to work alongside someone whose life transformed the world,” said Bill Hilf, CEO of Vulcan Inc., the company overseeing Allen’s interests in business and philanthropy. “All of us who had the honor of working with Paul feel inexpressible loss today. He possessed a remarkable intellect and a passion to solve some of the world’s most difficult problems, with the conviction that creative thinking and new approaches could make profound and lasting impact.”

Microsoft CEO Satya Nadella described Allen’s contributions as “indispensable,” and added that he “learned so much from him — his inquisitiveness, curiosity, and push for high standards is something that will continue to inspire me and all of us at Microsoft.”

“While most knew Paul Allen as a technologist and philanthropist, for us he was a much-loved brother and uncle, and an exceptional friend,” said Allen’s sister, Jody Allen. “My brother was a remarkable individual on every level.”

Thumbnail image courtesy of Vulcan Inc.