Mason died Thursday at his home in Newport Beach, his sister-in-law, Suzanne MacNeil, told the Associated Press. The cause was not disclosed, but his family said he suffered repeated concussions during his football career. He also had multiple knee and shoulder operations.
In 2011 Mason joined a class-action lawsuit filed by retired NFL players against the league claiming it knew or should have known the risk of brain damage from concussions and repeated head injuries.
Mason was born July 8, 1939, in Lake Charles, La., and played college football at Tulane in New Orleans.
He was the first overall selection by the expansion Vikings in the 1961 NFL draft. Choosing the Vikings over offers from the American Football League and the Canadian Football League, Mason was paid $12,000 his rookie season. With part of the money, he bought a silver Cadillac and adopted a pet monkey, which he named Dutch in honor of coach Norm Van Brocklin, according to the Minneapolis Star Tribune.
"I wasn't sure the AFL was going to last, and Canada seemed a long way away for a Louisiana boy," he told the Star Tribune in 2007. "There was some talk about an agent, but my dad, Bill, was a watchman at a chemical plant, and my mom, Mary, was a nurse, and they couldn't believe it … that this team from Minnesota was willing to pay their boy $12,000 to play football."
Mason, who was 6-1 and 195 pounds, played six of his 11 NFL seasons with the Vikings and became their first All-Pro player in 1963. He also was a kickoff and punt returner.
After the 1966 season Mason was traded to the Rams, along with tight end Hal Bedsole and a second-round draft pick, for the 15th overall pick in the 1967 draft. The Vikings used that pick to select Hall of Fame defensive tackle Alan Page.
Mason went on to play four years with the Rams and spent his final season, 1971, with the Washington Redskins. He finished his NFL career with 4,203 yards rushing, 2,324 yards receiving and 45 touchdowns. He earned a law degree after his career was over.