His death was confirmed Tuesday by Iowa State, where Orr led the Cyclones to a school-record 218 wins from 1980-94.
Orr spent 29 seasons as a Division I head coach. Twelve were at Michigan, where he guided the Wolverines to four NCAA tournament berths, the national title game in 1976 and 209 wins, the most in the school history.
Orr also spent three seasons at Massachusetts. The energetic and charismatic Orr finished with a career record of 466-346 and 10 NCAA tournament appearances.
"He was my hero," said Iowa State coach Fred Hoiberg, who grew up in Ames, Iowa, and played for three years under Orr.
Orr left UMass for Michigan and spent one season as an assistant before taking over as head coach in 1968.
Orr was twice named the Big Ten's coach of the year. In 1976, Orr was honored by the National Association of Basketball Coaches as its national coach of the year, and the Wolverines won the league title the following season.
Orr made the jump to Iowa State, then a struggling program, before the 1980-81 season and guided the program to its first NCAA tournament berth in 41 years in 1985.
A year later, Orr led the Cyclones in the Sweet Sixteen by beating Michigan. Iowa State would go on to reach the NCAA tournament four more times under Orr, whose up-tempo style and outgoing personality is viewed as the catalyst for the program's fervent following.
Orr would enter Hilton Coliseum to the "Tonight Show" theme and a trademark fist pump, helping cultivate a tremendous home-court advantage for the Cyclones. Iowa State beat 20 ranked opponents at home under Orr, who was honored with a statue inside the arena in 2011.
Orr coached 18 players who went on to the NBA, including Hoiberg and Jeff Hornacek.
"As a kid, just to see him walk out of that tunnel was what you waited for on game nights. Just to see his enthusiasm and passion. He was a father figure to so many of us. He impacted so many lives and made all of us better people. Not only was he a great basketball coach, he was even a better person," Hoiberg said.
Orr, who was born in Taylorville, Ill., is survived by his wife, Romie, and daughters Jennifer, Leslie and Rebecca.
Funeral arrangements are pending.