Mr. Donovan thrived in the National Football League when the fields were muddy, salaries were low and violence was the norm.
About 6-foot-2 and 275 pounds, he was a boulder on the Colts defensive line for most of a decade and was once cited by Sports Illustrated as “the toughest man in pro football.”
He helped his team, under coach Weeb Ewbank, win consecutive NFL championships in 1958 and 1959, defeating the New York Giants both times.
The Colts’ first title game, played at New York’s Yankee Stadium on Dec. 28, 1958, ended in a 17-17 tie, then went into a “sudden death” overtime period.
Mr. Donovan made a crucial tackle before the Colts offense, led by quarterback Johnny Unitas, drove 80 yards in the growing twilight to win the game, 23-17, on a one-yard plunge by fullback Alan Ameche.
The NFL’s first overtime game, witnessed by 40 million viewers on nationwide television, captured the public imagination and became known as “the greatest game ever played.”
Mr. Donovan was one of 12 Hall of Fame players to take part — six of them Colts — but at the time he was not aware of the game’s significance.
“We had no idea whatsoever that we were involved in something they call historic now,” he told the Baltimore Sun in 2008.
After Baltimore won its second straight NFL championship in 1959, beating the Giants 31-16, Sports Illustrated writer Tex Maule called the Colts “probably the best football team that ever played.”
Besides Unitas, Mr. Donovan’s Hall of Fame teammates included halfback Lenny Moore, wide receiver Raymond Berry, guard Jim Parker and defensive end Gino Marchetti.
Mr. Donovan, whose nickname was “Fatso,” was a gritty, trench-warfare player who excelled more through perseverance than style.
“He was strong and agile, a good athlete for a fat guy,” former teammate George Young, later general manager of the Giants, told Sports Illustrated in 1979. “Playing the line has more to do with feeling and reacting than with seeing, and Donovan was able to concentrate, recognize and react faster than anybody.”
He was a fearsome pass rusher but was particularly effective against the run.
He was named to five Pro Bowl teams before retiring after the 1961 season.
Mr. Donovan settled in Towson, Md., often appeared on local radio shows and made a series of commercials for the Maryland Lottery.
He owned a country club, where he did the painting and washed the pots and pans in the kitchen.
Even after he became a regular on Johnny Carson’s “Tonight Show” and “Late Night With David Letterman” in the 1980s, Mr. Donovan remained closely identified with his adopted city and the Colts, which deserted Baltimore for Indianapolis in 1984.