Elroy (Crazy Legs) Hirsch, an NFL Hall of Famer and former Wisconsin football hero, died early Wednesday of natural causes.
The 80-year-old Hirsch played just one season at Wisconsin (1942), but later returned to serve as the school's director of athletics from 1969-87.
His No. 40 is one of four numbers retired by the university.
"There has never been a more loved and admired ambassador for Badger sports than Elroy Hirsch," says Wisconsin director of athletics Pat Richter. "His charismatic and charming personality brought smiles to so many Badger fans.
"Anyone who came in contact with him enjoyed a special treat. He loved life, loved people and loved the Badgers.
"His passing is a huge loss to the Badger family. And our sympathies go to his family at this difficult time."
Hirsch played his professional career for the Chicago Rockets (1946-48) and Los Angeles Rams (1949-57), totalling 387 receptions for 7,029 yards and 60 touchdowns.
He was inducted into the NFL Hall of Fame in 1968.