Unknown to his family, Bryant had been under a doctor’s care when he died Tuesday at his home in Colorado Springs, Colo., said his sister-in-law, Wanda E. Bryant. She did not supply other details.

Bryant was the Rams’ second-round draft pick in 1973. He played with the team until 1982, was with the Seattle Seahawks in 1983 and 1984 and returned to the Rams for his last pro season in 1987.

In 13 NFL seasons, Bryant scored 23 rushing and receiving touchdowns and ran back kickoffs for three others. He ran for 3,264 yards in 849 carries, and caught 148 passes for 1,176 yards.

He ran for a 1-yard touchdown in the 1980 Super Bowl, which the Rams lost to the Pittsburgh Steelers, 31-19.

At 6-foot-1 and 234 pounds, he was the biggest player of the time to regularly return kickoffs.

“When Cullen hits those holes, nobody wants to stick their nose in there,” teammate Jack Youngblood told the Los Angeles Times in 1979. “Those little 180-pound (defensive backs) just jump on his back when he runs by.”

“He was an outstanding person with great character traits,” said Chuck Knox, Bryant’s coach with both the Rams and Seahawks. “When we asked him to do certain things, he’d do them. He never complained about anything. When he got that big body moving, it was something else, and he had muscles on top of muscles.”

Born William Cullen Bryant on May 20, 1951, in Fort Sill, Okla., Bryant attended high school in Colorado Springs and played football at Colorado University, where he received consensus All-American recognition.

In 1975, only two years after going to the Rams, Bryant went to federal court to challenge the right of then-NFL Commissioner Pete Rozelle to order him off the team. The Rams had signed former Detroit Lions receiver Ron Jessie. Under the “Rozelle Rule” on free agents, the team signing a free agent had to compensate the team that lost the player. If the teams couldn’t agree on compensation, the commissioner had the power to award either draft choices or players. He decided Bryant should go to Detroit.

At the behest of Rams owner Carroll Rosenbloom, Bryant went to court in Los Angeles. A judge was unsympathetic to the NFL’s position during a hearing, and the league backed off several days later before a ruling could be made.