Willie Wood, a Hall of Fame defensive back for the Green Bay Packers in the 1960s, who made a key interception that was considered the turning point in the first Super Bowl, died Feb. 3 at an assisted-living facility in Washington. He was 83.

The cause was complications from Alzheimer’s disease, said his legal adviser and former college teammate, Bob Schmidt.

Undrafted and unheralded out of college, Mr. Wood went on to play 12 years with Green Bay under coach Vince Lombardi and was a key part of one of the most storied dynasties in pro football history. During the 1960s, the Packers won five National Football League championships and the first two Super Bowls.

Mr. Wood made eight Pro Bowl teams and was the dominant free safety of his era. He still holds the NFL record for most consecutive games started by a safety, with 154. At 5-foot-10 and about 190 pounds, he was one of the Packers’ smallest players — and one of the most respected.

“Next to Lombardi, Wood scares his own teammates more than anybody else does,” offensive guard Jerry Kramer wrote in his account of the Packers’ 1967 season, “Instant Replay.”

“Wood even scares Ray Nitschke” — Green Bay’s fearsome middle linebacker, whose front teeth were missing. “‘I hate to miss a tackle,’ Ray says, ‘ ’cause if I do, I know I’m gonna get a dirty look from Willie. He’ll kill you with that look.’ ”

Mr. Wood was the last player Lombardi named to the Packers roster in 1960. When the Baltimore Colts’ Raymond Berry scored two touchdowns against him in a game, Mr. Wood said, “I thought my pro career was ended. They were the worst boo-boos I ever made. I figured my mistakes lost the game.”

Veteran players grumbled at him, but Lombardi told Mr. Wood, “Don’t you believe anything those fellows say,” according to David Maraniss’s 1999 biography of the coach, “When Pride Still Mattered.” “Every one of those guys making fun of you has had the same thing happen to them. You’re going to be here as long as I’m here.”

During his first two seasons in Green Bay, Mr. Wood was mentored by Emlen Tunnell, a veteran defensive back who was the first African American player inducted into the Pro Football Hall of Fame. Mr. Wood took over as the starting free safety in 1961, helping on pass coverage and often standing as the last defender of the Packers’ goal line.

“His pregame ritual was to sit alone at his cubicle, chewing worriedly on a fresh white towel, then another one,” Maraniss wrote, “before he traipsed over to the bathroom and threw up. But once he took the field, he was all intuition and grace: No. 24 in green and gold, closing ground in a sudden burst to knock away a pass or upend a runner with his unorthodox tackle, flinging his body at the ballcarrier’s ankles, cutting the feet out from under him so that he flipped wildly into the air, cleats over helmet.”

He leveled players who outweighed him by 40 pounds, yet was quick enough to be a dangerous punt returner, twice leading the NFL in average yards per return. He picked off a league-leading nine passes in 1962 and had 48 interceptions for his career — the second most in team history.

Perhaps his most important interception came in Super Bowl I, played Jan. 15, 1967, between the Packers and the Kansas City Chiefs, champions of the rival American Football League.

“Past scores … heights, sizes, weights — none of that means a thing,” Mr. Wood said before the game. “The only thing that counts is combat, head to head, for 60 minutes on the field.”

Green Bay was clinging to a 14-10 lead early in the third quarter when Chiefs quarterback Len Dawson threw under heavy pressure from the Packers’ front line.

“His pass just floated out there with nothing on it,” Mr. Wood recalled 30 years later to the Los Angeles Times. “It was an easy interception.”

He caught the ball and returned it 50 yards before being dragged down on the Kansas City 5-yard line.

The Packers’ Elijah Pitts scored on the next play, as the Packers went on to dominate the second half and win easily, 35-10.

“That play seemingly changed the personality of the game,” Kansas City coach Hank Stram said afterward. “After that, we just broke down.”

Lombardi described the interception as “Willie Wood at his finest.”

William Vernell Wood was born Dec. 23, 1936, in Washington. His parents were divorced when he was young, and he was raised largely by a single mother and grandmother.

District schools were still segregated when Mr. Wood attended the old Armstrong High School, where he excelled in football, basketball and baseball.

After a year at a junior college in California, he enrolled at the University of Southern California in 1957 and became the first African American quarterback in the old Pacific Coast Conference (now the Pac-12).

As a senior in 1959, Mr. Wood led the Trojans to an 8-2 record. He was also a standout defensive back and place-kicker, but he was not chosen in the pro football draft. He wrote letters to three teams — the New York Giants, the San Francisco 49ers and the Packers — asking for a tryout. The only team to respond was the Packers.

Lombardi recognized a fierce competitiveness in Mr. Wood, Maraniss wrote in “When Pride Still Mattered,” “along with some unteachable traits: he was fearless, quick and agile, able to touch the top of the goalpost crossbar” — 10 feet off the ground — “with his elbow from a standing leap.”

At first, Mr. Wood felt awkward in Green Bay, where he lived at the YMCA for $1.50 a night during his rookie season.

“I had never been in a place where there weren’t any black folks,” he told the Milwaukee Journal Sentinel in 2002.

In 1960, Lombardi summoned his players together and told them that he would not tolerate racial bias or name-calling of any kind.

“If I ever hear … anything like that around here, regardless of who you are, you’re through with me,” he said, according to Maraniss’s biography. “You can’t play for me if you have any kind of prejudice.”

Mr. Wood, who called Lombardi “perhaps the fairest person I ever met,” was fully aware that the Washington Redskins in his hometown had not yet allowed a single black player on the team’s roster.

During the offseasons, Mr. Wood returned to Washington, where he taught at a junior high school and was asked by the D.C. government to be a mediator in disputes between rival gangs.

He retired after the 1971 season and became an assistant coach with the San Diego Chargers. In 1975, he was named head coach of the Philadelphia Bell of the upstart World Football League, making Mr. Wood the first African American head coach in modern-day professional football. The league soon folded, and Mr. Wood moved to the Toronto Argonauts of the Canadian Football League, where he also became the first black head coach.

He was disappointed that he was never offered another coaching job in the NFL. Instead, he founded a Washington-based mechanical contracting business, which he ran until 2001.

His wife of 20 years, the former Sheila Peters, died in 1988. Survivors include their two sons, Andre Wood of San Francisco and Willie Wood Jr., a former high school and professional football coach, of Washington; a daughter from an earlier relationship, LaJuane Wood of Seat Pleasant, Md.; a sister, Gladys Hawkins of Glenarden, Md.; six grandchildren; and five great-grandchildren.

In later years, Mr. Wood felt the punishing effects of his football career. He had back surgery, knee and hip replacement and, after about age 70, suffered from progressive dementia.

“The game takes a toll,” he said in 2002, then added: “I have no regrets about my career whatsoever. I got more out of it than anyone would have ever imagined.”

In 1989, Mr. Wood was inducted into the Pro Football Hall of Fame in Canton, Ohio, where several of his teammates are also enshrined, along with Lombardi.

“When I first walked into the Packer camp, there was no doubt who was in charge,” Mr. Wood told The Washington Post that year. “The first time I met Vince Lombardi, he scared the hell out of me. And I’ve been shaking ever since.”