Allen's sister, Jody, said he 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. Paul's family and friends were blessed to experience his wit, warmth, his generosity and deep concern," she said in a statement. "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."
Allen ranked among the world's wealthiest individuals. As of Monday afternoon, he ranked 44th on Forbes' 2018 list of billionaires with an estimated net worth of more than $20 billion.
Through Vulcan, Allen's network of philanthropic efforts and organizations, the Microsoft co-founder supported research in artificial intelligence and new frontier technologies. The group also invested in Seattle's cultural institutions and the revitalization of parts of the city.
Allen owned two professional sports teams, the NFL Seattle Seahawks and NBA Portland Trailblazers. He was also an electric guitarist who occasionally jammed with celebrity musicians including Bono and Mick Jagger, and a huge music fan. He funded and designed the Experience Music Project in Seattle, devoted to the history of rock music and dedicated to his musical hero Jimi Hendrix. (It has since been re-christened the Museum of Pop Culture.) The building was designed by architect Frank Gehry to resemble a melted electric guitar.