Mercury Morris, Elusive Rusher on a Perfect Dolphins Team, Dies at 77

Part of a talented backfield triumvirate that also included Larry Csonka and Jim Kiick, he helped lead Miami to two Super Bowls and an undefeated season.

Mercury Morris, who gave speed and dexterity to the rushing attack of the Miami Dolphins in the early 1970s, helping to power the team to two Super Bowls and the only perfect season in the history of the National Football League, died on Saturday night. He was 77.

His son Troy announced the death in a statement that did not specify the cause or where Morris was at the time.

During a six-year tenure with the Dolphins, from 1969 to 1975, Morris qualified for the Pro Bowl three times.

At the height of his career, Morris was part of an unusual three-man rushing rotation alongside the fullback Larry Csonka and another running back, Jim Kiick. Csonka and Kiick were powerful bruisers; Morris, who was born Eugene, gained his nickname from his quicksilver unpredictability on the field.

Initially, he had been used mainly as a kick returner. He did not get a single handoff during the Dolphins’ loss to the Dallas Cowboys in the 1972 Super Bowl. Csonka and Kiick, conversely, gained such fame for their partnership on the field and their friendship off it that they were nicknamed Butch Cassidy and the Sundance Kid.

The next season, Coach Don Shula made Morris an integral part of the offense.

“Merc is the guy that can go into the ballgame and get you moving if you’re not moving,” Shula told reporters.

To assert his new position on the team, Morris would deliberately sit between Csonka and Kiick on the bench. Journalists began writing about Kiick’s wounded pride. Soon enough, however, he began praising Morris.

“I used to think, ‘Wow, I feel really fast on this turf,’” Kiick recalled in “The Perfect Backfield,” a 2014 documentary about him, Csonka and Morris. Later, he continued, “I’d go, ‘What the hell does Mercury feel like?’”

After quarterback Bob Griese broke his ankle in Week 5, the running game became even more important for the team.

Behind an offensive line featuring future Hall of Famers like Larry Little and Jim Langer, the three backs proved to be unstoppable. In the regular season, the offense averaged 27.5 points a game, leading the N.F.L., and Morris rushed for a league-leading 12 touchdowns.

He and Csonka became the first two players on the same team to gain 1,000 or more rushing yards. And Kiick wound up getting plenty of touches and receptions, recording 10 touchdowns and nearly 800 yards from scrimmage.

The Dolphins won their 19th consecutive game in the 1973 Super Bowl in a game dominated by their defense, which held the Washington team, then called the Redskins, to a single touchdown.

The next season, Morris led the N.F.L. with 6.4 yards per carry, and the Dolphins were dominant again, losing just two games en route to another Super Bowl victory.

After that, however, injuries and rival offers broke apart the team’s rushing triumvirate. Lured by a big payday, Csonka, Kiick and the wide receiver Paul Warfield left the Dolphins to play for the newly formed World Football League. When that endeavor flopped, all three players returned to different N.F.L. teams.

Morris gained the chance to be the Dolphins’ premier running back. But a series of health issues, particularly an old neck injury, thwarted him in the next few seasons. After being waived by the Dolphins after the 1975 season, he spent a single season with the Chargers and then quit football.

To cope with severe headaches, Morris began using drugs. In 1982 he returned to the national news, not for football but instead for being sentenced to 20 years in prison after convictions on several charges related to cocaine trafficking. The convictions were later overturned, and Morris spent years making the case that he had been innocent of crimes other than drug use.

Eugene Edward Morris was born in Pittsburgh on Jan. 5, 1947. He grew up playing touch football in a friend’s backyard. In “The Perfect Backfield,” he said he never lost the sense that the goal of football was for nobody to be able to touch you.

As a running back at West Texas State, Morris vied with O.J. Simpson — like Kiick, a rival who became a friend — for the national college rushing title.

In 1986, after Morris had served three and a half years in prison, the Florida Supreme Court ruled that evidence he had offered in support of his defense — that he was the victim of entrapment — had been wrongfully suppressed at trial. He then agreed to a settlement for time already served, wrote a memoir and began a lucrative career as a public speaker.

In addition to Troy, his survivors include four other children, Geno, Maceo, Tiffany and Elliott, and three sisters, Cynthia, Valerie and Janice.

In 2022, Morris described Kiick’s struggles with chronic traumatic encephalopathy, also known as C.T.E., to The New York Times. He said that he had to coax Kiick out of his car and direct him to an airport terminal to bring him to the filming of “The Perfect Backfield.” But even when Kiick’s dementia became severe, Morris continued seeing him about every week.

Ken Belson contributed reporting.