John Henry Johnson, 81, a durable Hall of Fame fullback who was known as one of the toughest players in the hard-nosed National Football League of the 1950s and 1960s, died June 3 in Tracy, Calif. The cause of death was not announced, but he had reportedly had Alzheimer’s disease for several years.

Mr. Johnson, who played from 1954 to 1966, began his NFL career with the San Francisco 49ers as part of the team’s “Million Dollar Backfield” and went on to become one of football’s top ground gainers in the early 1960s with the Pittsburgh Steelers.

In 1962, at the advanced football age of 33, he became the first Steeler to rush for more than 1,000 yards in a season. He duplicated the feat when he was 35.

Earlier, he helped lead the Detroit Lions to the NFL championship in 1957.

Mr. Johnson, who was known by all three of his names, emerged in the NFL when pro football games sometimes resembled back-alley brawls. Players throughout the league came to fear No. 35, whose crushing blocks and tackles broke the jaws of at least two players, including one teammate in an intra-squad scrimmage.

“What did you want me to do?” an unapologetic Mr. Johnson asked. “Kiss the guy or tackle him?”

Despite the dangers of his sport, Mr. Johnson wore just a single-bar face mask on his helmet and no pads or gloves on his hands. At 6 feet 2 and 225 pounds, he had excellent speed but was better known as a powerful runner and punishing blocker. His stiff-arm — essentially an open-palm punch to the jaw while running at full speed — was devastating.

“If you didn’t keep your eye on him,” Wayne Walker, a former linebacker with the Lions, told the San Francisco Chronicle, “next thing you know you’d have your jaw wired.”

Early in his career, Mr. Johnson was part of the 49ers’ “Million Dollar Backfield,” which included quarterback Y.A. Tittle and running backs Hugh McElhenny and Joe Perry, who died April 25. They are the only four members of the same NFL backfield to be elected to the Pro Football Hall of Fame.

Mr. Johnson was a primary blocker for his teammates but also managed to run for 681 yards in his rookie season of 1954, finishing second to Perry as the NFL’s top rusher.

Although overshadowed by Perry and later by fullbacks Jim Brown of the Cleveland Browns and Jim Taylor of the Green Bay Packers, Mr. Johnson was considered one of the NFL’s finest players at his demanding position.

He finished among the top 10 in rushing seven times without ever leading the league. When he gained 1,141 yards in 1962, he finished second to Taylor. Two years later, when Mr. Johnson ran for 1,048 yards, he was third in rushing yardage behind Brown and Taylor.

“He was a wild man, legs and arms and elbows and knees going every which way when he was running,” Perry told California’s Contra Costa Times newspaper in 2006. “And John was tenacious at all times. If you wanted to [label] him, you would say he was one of the meanest SOBs that got on the football field.”

John Henry Johnson was born Nov. 24, 1929, in Waterproof, La., and bore the same name as the legendary “steel-driving man” who, according to folklore, could pound railroad spikes faster than a steam-powered hammer.

Mr. Johnson grew up in Pittsburg, Calif., where he was a star high school football and basketball player and was the state champion in the discus throw.

He attended St. Mary’s College of California, then, when the school eliminated football, transferred to Arizona State University. He played one year in Calgary, Alberta, with the Canadian Football League before joining the 49ers.

After three seasons in Detroit, Mr. Johnson played in Pittsburgh from 1960 to 1965 before a final season with Houston Oilers in 1966. When he retired, his 6,803 career yards ranked fourth in pro football history.

He later worked for a county community services department in Pittsburgh. He had five children, but complete information about survivors could not be confirmed.

His finest game, Mr. Johnson acknowledged when he was elected to the Hall of Fame in 1987, came on Oct. 10, 1964, in Cleveland against the arch-rival Browns. Before more than 80,000 fans, Mr. Johnson outshone Cleveland’s Jim Brown, who is considered to be one of the greatest football players of all time.

Mr. Johnson took a first-quarter handoff the Browns’ 33-yard line, drove his shoulder into a defensive back and didn’t stop until he had reached the end zone. In the second quarter, he took a pitchout, eluded two players at the 20-yard line and raced for a 45-yard touchdown. He later scored on a four-yard run.

Mr. Johnson gained 200 yards in 30 carries as Pittsburgh upset the Browns, 23-7. It was the first time any Steeler had run for 200 yards.

“It was like he saved his best games for the Browns,” teammate Clendon Thomas told the Pittsburgh Post-Gazette in 1994. “Every game it seemed like he would outrun, outcatch and outblock Jim Brown. I think John Henry wanted everyone to know that he was a pretty good fullback, too.”