John P. Reardon — Jack to everyone who knew him — had a superpower for seeing others’ potential when they couldn’t see it themselves. Whether it was a high school kid applying to Harvard College, a struggling student athlete, or one of the countless colleagues who sought out his advice, Reardon devoted his more than six decades at Harvard not just to the institution but to the people who define and animate its mission.

“There are hundreds of stories like that,” said Tom Reardon about his brother, “where at just the right moment he was able to encourage somebody or open their eyes to their own potential, or provide a thought that then changed the course of how they were going at things, so it was an amazingly well-lived life.”

Reardon, whose leadership posts at Harvard included director of admissions, director of athletics, and executive director of the Harvard Alumni Association, died June 23 at his home in North Weymouth. He was 88.

“Jack Reardon was an extraordinary member of our community whose love and respect for Harvard drew out the best in all of us,” President Alan Garber said. “He is one of a few people who devoted much of his adult life to Harvard while truly living the values and highest character of our University — the best of the University personified. He will be much missed, but his legacy of commitment, humility, and friendship will live on for years to come.”