Sullivan played quarterback for the Tigers between 1968 and 1971, going on to win the coveted Heisman in his final year.
"He was a friend, a mentor and a man of character who was loved by many generations of Auburn fans".
Sullivan's family issued a statement that he had "died peacefully at home" Sunday morning, surrounded by parents.
"We are deeply saddened by the passing of Pat Sullivan, one of Auburn's all-time greats on and off the field", Tigers coach Gus Malzahn said in a news release.
Sullivan led the nation in full attack as a junior in 1970, teaming with wide receiver Terry Beasley for a 2.586-yard pass. Sullivan was identified with throat most cancers in 2003 and the assertion mentioned he "fought a long and hard battle as a result of his treatments". He served as UAB's offensive coordinator from 1999-06 and finished his career as Samford's head coach from 2007-14. The fight for Sullivan's commitment between Auburn coach Shug Jordan and Alabama coach Paul Bryant made him a star while he was still in high school at Birmingham's John Carroll Catholic.More news: Sub Lieutenant Shivangi Navy’s first woman pilot
The Auburn Tigers and broader college football world are mourning the loss of one of the program's greatest players. "I'll perpetually be indebted to Coach Sullivan for serving to deliver me again to Auburn to function the pinnacle soccer coach".
Sullivan was an All-American and SEC Player of the Year his last two seasons.
Freshmen weren't eligible for varsity competition when Sullivan arrived on the Plains, so he had to wait until 1969 to take his first snaps for Auburn.
Sullivan led Auburn out of a 17-0 hole in the 1970 Iron Bowl to a 33-28 victory, followed by a 35-28 victory over Archie Manning and Ole Miss in the Gator Bowl on January 2, 1971. His 53 career passing touchdowns remain an Auburn record.
Sullivan's three seasons at Auburn ended in bowls - and he won the MVP award in two of them.More news: Apple Names Spectre Camera the Best iPhone App of 2019
In 1986 he joined Coach Pat Dye's staff as quarterbacks coach at Auburn.
In 1991, Sullivan was elected to the National Football Foundation and College Hall of Fame.
He entered the Alabama Sports Hall of Fame in 1981.
Sullivan is survived by his spouse, the previous Jean Hicks, and their three youngsters - Kim, Kelly and Patrick Jr.More news: Google’s great Photos app is now a chat app, too
Sullivan coached at TCU from 1992-97 where he compiled a record of 24-42-1. "He was a kind and humble gentleman, who was an Auburn legend", Auburn athletics director Allen Greene said in a statement.