Paul Allen, the school-mate who worked with Bill Gates and persuaded him for a drop-out from Harvard to start Microsoft, has passed away at the age of 65. According to a statement released by his family, Allen died of complications that had risen up due to non-Hodgkin’s lymphoma, a type of cancer.

Allen had left Microsoft in 1983 due to a widely documented dispute with Gates. However, by the virtue of him continuing to hold the same share of partnership as he signed up for in the beginning of Microsoft, he continued to be seen as a co-founder. He also amassed sizeable wealth over the past few decades, owing to that initial partnership.

In early October, Allen had revealed he was being treated for the non-Hodgkin’s lymphoma, which he also was treated for in 2009. He had an earlier nudge with Hodgkin’s lymphoma, another cancer, in the early 1980s before leaving Microsoft.

Allen had been widely regarded for his massive philanthropic work, however largely avoiding the limelight. He remained extremely committed to the Pacific Northwest region, directing more than $1 billion to mostly local philanthropic projects, developing Seattle’s South Lake Union tech hub, the same hub which is now home to Amazon.

Current Microsoft Chief Executive Satya Nadella on Monday called him a “quiet and persistent” man who changed the world.