T. Boone Pickens, an Oklahoma State alumnus and one of the university’s largest donors, passed away from natural causes at his home in Dallas, Texas on Wednesday. Pickens was 91-years-old. The Dallas News reported the news.

Beginning his career with Phillips Petroleum, Pickens transitioned into other projects throughout his life and owned his own energy company, Mesa Power LP.

Possessing an estimated net worth of $500M in November 2016, Pickens gave hundreds of millions of dollars to the athletic programs of his beloved Cowboys.

Due to his generosity toward the university, Oklahoma State officially renamed their football stadium “Boone Pickens Stadium” during a 2003 game vs. Wyoming.

The T. Boone Pickens Foundation issued the following statement on Twitter:

As influential as any booster in the sport, Pickens’ presence will be missed throughout college football.

Oklahoma State travels to Tulsa to face the Golden Hurricane on Saturday (3:30PM ET, ESPN2).