Earl Morrall, right, with Miami Dolphins coach Don Shula. Mr. Morrall came off the bench to lead the Baltimore Colts to the Super Bowl in 1968 and the Dolphins to a perfect season in 1972. (AP)

Earl Morrall, who came off the bench to lead two teams to the Super Bowl, including the Miami Dolphins during their unprecedented perfect season in 1972, and who may have been the greatest backup quarterback in NFL history, died April 25 in Fort Lauderdale, Fla. He was 79.

He had Parkinson’s disease. His death was announced by the Dolphins and the National Football League.

Mr. Morrall played for six teams during his 21 years in the NFL, and for much of that time he was an understudy to superstars. At various times, he played with no fewer than five future Hall of Fame quarterbacks: Y.A. Tittle, Len Dawson, Fran Tarkenton, Johnny Unitas and Bob Griese.

In 1967, his career seemed to be winding down. He threw only 24 passes for the New York Giants that year before moving on to Baltimore the next season. When the Colts’ quarterback, Unitas, injured his elbow during the preseason, the 34-year-old Mr. Morrall took over.

Under coach Don Shula, Mr. Morrall blossomed into an unexpected star. He led the Colts to a 13-1 record in what remains the best season in franchise history. He passed for a league-leading 26 touchdowns and was named the NFL’s most valuable player.

This 1968 photo shows Baltimore Colts quarterback Earl Morrall throwing a pass during the Colts 28-24 victory over the Los Angeles Rams. (NFL/AP)

The Colts won two more games in the playoffs before going on to meet the New York Jets in the third Super Bowl game ever played. The Jets’ brash quarterback, Joe Namath, had promised a victory over the heavily favored Colts.

Mr. Morrall and his team struggled throughout the game. Late in the first half, in a play that could have tied the game, he did not see a wide-open receiver, Jimmy Orr, in the end zone and instead threw the ball over the middle, where it was intercepted.

Two more of his passes were picked off that day, and Mr. Morrall was eventually replaced by Unitas. The Colts lost to Namath’s Jets, 16-7, in what remains one of the most memorable upsets in football history.

Mr. Morrall redeemed himself two years later when he stepped in for an injured Unitas in Super Bowl V and engineered a 16-13 come-from-behind victory for the Colts over the Dallas Cowboys.

In 1972, with Shula building a new dynasty in Miami, Mr. Morrall signed with the Dolphins as the second-string quarterback behind Griese. In the fifth game of the season, against the San Diego Chargers, Griese suffered a broken leg and dislocated ankle and was taken off the field on a stretcher.

Mr. Morrall, then 38 and the oldest player on the team, was forced into action. Years later, lineman Bob Kuechenberg recalled how Mr. Morrall broke the tension when he entered the huddle.

“All right,” he said, “anyone know any dirty jokes?”

Steady and unflappable, Mr. Morrall took over and guided the Dolphins down the field to a touchdown.

“When Griese got hurt, I wasn’t looking to be a superstar,” Mr. Morrall told the Chicago Sun Times in 2007. “Bob got hurt on second down. I was just thinking about third down. I wanted to get a first down. I wanted to stay on an even keel and keep moving down the field.”

The Dolphins won that game and didn’t stop.

For nine consecutive weeks, with Mr. Morrall at at the helm, the Dolphins won every time they took the field. They had a powerful running attack, with Larry Csonka, Mercury Morris and Jim Kiick gaining more than 2,500 yards among them. The tenacious defensive unit, without any major stars, became known as the No-Name Defense.

And at the center of it all was Mr. Morrall, his helmet covering a crewcut that was already a decade out of date.

On Nov. 19, he faced Namath, his long-haired nemesis from the Jets. During the third quarter of the Dolphins’ 28-24 comeback victory, Mr. Morrall scrambled around left end and raced 31 yards into the end zone to score a key touchdown. It was the Dolphins’ longest touchdown run of the season.

At year’s end, the Dolphins had a perfect 14-0 record, the first time an NFL team had gone through a full season without losing or tying a game. Mr. Morrall won the NFL’s first Comeback Player of the Year Award, and his clutch performance that year has entered football lore.

In the playoffs, the Dolphins kept rolling, defeating the Cleveland Browns and the Pittsburgh Steelers on their way to the Super Bowl, where they would meet the Washington Redskins in the Super Bowl on Jan. 14, 1973.

By then, Griese had recovered from his injuries, and, over Mr. Morrall’s objections, Shula tapped him to start the game. The Dolphins won the Super Bowl, 14-7, to finish the year with a record of 17-0.

Thirty-five years later, the New England Patriots were undefeated during the 2007 NFL season, but they lost to the New York Giants in the Super Bowl. After more than 40 years, no other team in any major professional sport has been able to match the Dolphins’ perfect season.

Earl Edwin Morrall was born May 17, 1934, in Muskegon, Mich. At Michigan State, he was an all-American quarterback and led the Spartans to victory over UCLA in the 1956 Rose Bowl, 17-14.

Mr. Morrall was also a star infielder on Michigan State’s baseball team, and he is believed to be the only person to have played in the College World Series, Rose Bowl and Super Bowl.

After college, he played one season with the San Francisco 49ers before being traded to the Pittsburgh Steelers and later to the Detroit Lions and New York Giants. He won his third Super Bowl championship ring in 1974 with the Dolphins and threw the last of his 161 career touchdown passes in 1976, when he was 42.

From 1979 to 1983, he was the quarterbacks coach at the University of Miami, where his proteges included Jim Kelly, Bernie Kosar and Vinny Testaverde.

For many years, Mr. Morrall lived in Davie, Fla., outside Fort Lauderdale, in a futuristic house designed like a spaceship. He became the town’s mayor and was instrumental in getting the Dolphins to establish their off-season training camp in Davie.

He made an unsuccessful run for the state legislature as a Republican in 1992 and later settled in Naples, Fla.

Survivors include his wife, Jane Morrall; five children; and nine grandchildren.

Mr. Morrall was often asked what it took to come off the bench and be effective as a quarterback and team leader in the NFL.

“When you get the chance to do the job, you have to do the job,” he said in 1989. “That’s all there is to it.”