Forrest Gregg, one of pro football’s most formidable blockers, who didn’t miss a game in 15 years as a mainstay of the Green Bay Packers dynasty of the 1960s and was described by his coach, Vince Lombardi, as “the finest player I ever coached,” died April 12 at a hospital in Colorado Springs, where he lived. He was 85.

His death was announced by the Pro Football Hall of Fame, which enshrined Mr. Gregg in 1977. He had complications from Parkinson’s disease.

As pro football began to capture the public imagination, Mr. Gregg became an anchor of the Green Bay offensive line from his right tackle position. He played in 188 consecutive games — a National Football League record at the time — and was a member of six teams that won the NFL title, including the first two Super Bowl champions.

After a stellar college career at Southern Methodist University in Dallas, Mr. Gregg joined the Packers in 1956. He said he had to look in an atlas to learn which state Green Bay was in.

The Packers were then one of the NFL’s worst teams and finished 1-10-1 in 1958, the year before Lombardi took over as coach. During Lombardi’s first season, the Packers had a winning record, 7-5. The next year, 1960, they reached the NFL championship game, only to lose to the Philadelphia Eagles, 17-13.

Mr. Gregg was a key part of the rebuilding of the Packers and was one of Lombardi’s most astute proteges. He constantly studied film to gain an edge over his opponents and worked in the offseason to maintain his agility and strength.

As teammates in the NFL’s smallest city, the Packers developed a sense of camaraderie perhaps unmatched in football history. The team won the NFL title in 1961, 1962 and 1965, then triumphed in the first two Super Bowls, played after the 1966 and 1967 seasons against the champion of the rival American Football League.

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“We weren’t representing just the Green Bay Packers,” Mr. Gregg said in 1991 about the first Super Bowl, in which Green Bay defeated the Kansas City Chiefs, 35-10. “We were representing the NFL. We were the senior league and had all the tradition and everything else. We just didn’t want to get beat by them.”

NFL historians generally rank Lombardi’s Packers of the 1960s as the greatest dynasty in pro football history. No fewer than 12 members of the team have been inducted into the Pro Football Hall of Fame.

In addition to Mr. Gregg, Green Bay’s offense included Hall of Famers Jim Ringo at center and Jerry Kramer at right guard, with a backfield featuring quarterback Bart Starr and running backs Jim Taylor and Paul Hornung.

They had a simple attack, built on power, quickness and precise execution. During an era when offensive lineman were not allowed to use their hands, the 6-foot-4, 249-pound Mr. Gregg relied on footwork, balance and explosiveness to land crushing blocks on defensive ends and linebackers.

“He’s great on pass protection,” Starr was quoted as saying in Pro Football Weekly, “but where he separates himself from the other tackles is the way he hustles downfield for an extra block, even when the play goes the other way.”

Mr. Gregg played in burning heat, sticky mud and on Green Bay’s “frozen tundra,” most memorably in the 1967 “Ice Bowl” against the Dallas Cowboys. With a game-time temperature of 13 degrees below zero, the Packers persevered to win the NFL championship in the last 13 seconds, as Starr sneaked across the goal line. A linebacker blocked by Mr. Gregg fell helplessly on top of Starr in the end zone.

The durable Mr. Gregg was planning to retire in 1969 but returned for two more years with the Packers, then played a final season with the Cowboys’ Super Bowl-winning 1971 team. He never missed a game from his rookie season in 1956 until 1971. He was a first-team All Pro player eight times and was one of four players in NFL history to have played on six championship teams.

After Lombardi’s death from cancer in Washington in 1970, Mr. Gregg visited his coach’s widow, who handed him a book her husband had compiled.

“She had a bookmark on this certain page,” Mr. Gregg told the Green Bay Press-Gazette in 2010. “Being curious, I just opened it up to that bookmark, and I started reading it and . . . Vince said, ‘Forrest Gregg quite simply was the finest player I ever coached.’ And man, you can’t imagine in your mind how I felt. I still get emotional about it when I read it or hear it.”

Alvis Forrest Gregg was born Oct. 18, 1933, in Birthright, Tex. He was one of 11 children and grew up on a family farm.

He excelled in sports, particularly baseball, but knew about football only from the radio.

“It became an obsession,” he told the Chicago Tribune in 1987. “I never played in a football game until I was in high school. Never saw a football game until I was 15.”

At Southern Methodist, he was an all-conference player and, during his senior season, was named to all-American teams. He joined the Packers in 1956, then missed the next season while serving in the Army. During the offseasons, he returned to SMU and completed his bachelor’s degree in physical education in 1959.

After retiring as a player, Mr. Gregg turned to coaching, first with the Cleveland Browns and later in the Canadian Football League. Returning to the NFL, he led the Cincinnati Bengals to the Super Bowl in 1982, only to lose to the San Francisco 49ers.

He became the head coach in Green Bay in 1984, hoping to restore the Packers’ winning ways, but the hard-nosed style he learned from Lombardi seemed out of step with the times. In four years with the Packers, Mr. Gregg’s coaching record was a dismal 25-37-1.

In 1988, SMU brought him back to rebuild the football program, which had been shut down by the NCAA because of repeated recruiting violations and payments to players.

Mr. Gregg built the team from scratch and coached it for two seasons, compiling a record of 3-19. He also served as SMU’s athletic director. Asked what he would do if he encountered the boosters who had given college athletes money under the table, he said, “Knock ’em right in the mouth.”

Mr. Gregg’s survivors include his wife of 58 years, Barbara Dedek Gregg of Colorado Springs; two children; and several brothers and sisters.

In 2009, Mr. Gregg published a memoir, “Winning in the Trenches.” He twice overcame cancer before he was diagnosed with Parkinson’s disease.

“You know something, how in the world could I ever want to change anything that happened to me as a football player?” he told the Press-Gazette. “I didn’t know how to put on a uniform in 1948, when I first started playing football, to being on all those championship teams and playing for a guy like Vince Lombardi. . . . It was an experience of a lifetime.”