James Thomas Treleaven passed away on February 9th, 2026 after a diagnosis of lymphoma in January. He is survived by his parents Sharleen and David, his brothers Courtenay, Derek and Dwayne, his nieces Robin and Rachel, his grandniece Sequoia, Courtenay’s partner Joanna, and her daughters Karolina and Alexandra.

Born in Saskatoon, Saskatchewan in 1965, James grew up in Crystal Beach in Nepean, Ontario, where he met friends Dave, Mark, Leanne and others. He attended Bell High School, where he developed a keen interest in the emerging field of computer science. He studied at the University of Waterloo from 1984, where he made a number of good friends, including Wayne and Karl. He graduated in 1988 with a mathematics degree and went on to a career in software development and artificial intelligence.

James was always a voracious reader, and had a tremendous appetite for learning. He enjoyed intellectual conversation and debating a wide range of important topics, particularly those relating to global geopolitics. An avid traveller, James was interested in exploring new regions, peoples and cultures. On many occasions he cited the Okavango Delta in Botswana as one of his most exotic and extraordinary travel destinations and life experiences. In the mid 1990s, he spent time teaching English in Poland where he met his good friend Dave.

The family extends a heartfelt thank you to everyone at the Mount Sinai Hospital and Princess Margaret Cancer Centre in Toronto, as well as the Bruyère Saint-Vincent Hospital in Ottawa, who made the journey and tribulations of his last weeks as comfortable as possible. We are grateful for the support from doctors, nurses, and others.

A private memorial will take place at a future date.

In lieu of flowers, donations in honour of James can be made to UNH Princess Margaret Cancer Foundation.