San Francisco Giants player Willie McCovey in 1964. (AP/AP)

Willie McCovey, a Hall of Fame slugger and onetime National League Most Valuable Player who was a teammate of Willie Mays with the pennant-winning San Francisco Giants in the 1960s, died Oct. 31 at a hospital in Stanford, Calif. He was 80.

His death was announced by the Giants. The cause was not disclosed, but the San Francisco Chronicle reported that Mr. McCovey, who had used a wheelchair for several years, was hospitalized for an infection.

Mr. McCovey, who was nicknamed “Stretch” for his rangy 6-foot-4 frame, was recognized as one of the most fearsome hitters of his time. In his first big-league game, on July 30, 1959, he hit two singles and two triples off Hall of Fame pitcher Robin Roberts.

Playing just two months of that season, Mr. McCovey compiled an average of .354 with 13 home runs and 38 RBIs and was unanimously named Rookie of the Year.

Despite suffering knee and foot injuries, Mr. McCovey went on to hit 521 home runs in a 22-year career, 19 of which were with the Giants, who played in San Francisco’s cavernous, windblown Candlestick Park.

“You knew right away he wasn’t an ordinary ballplayer,” Hank Aaron, who often battled Mr. McCovey for the home-run title, said in a statement released by the National Baseball Hall of Fame. “He was so strong, and he had the gift of knowing the strike zone. There’s no telling how many home runs he would have hit if those knees weren’t bothering him all the time and if he played in a park other than Candlestick.”

Willie McCovey, right, is congratulated by Hank Aaron (44) and Ron Santo after hitting a home run in the 1969 All-Star Game. (AP/AP)

Despite playing only part time in 1962, Mr. McCovey helped lead the Giants to the World Series against the New York Yankees. He hit a home run off the Yankees’ Ralph Terry in San Francisco’s 2-0 victory in Game 2.

In the seventh and decisive game, played at Candlestick Park, Mr. McCovey came to the plate to face Terry again in the bottom of the ninth inning. The Giants trailed, 1-0, with two outs and had runners on second and third. A base hit by Mr. McCovey would almost surely have given San Francisco its first World Series title.

He hit a screaming line drive — the hardest ball he ever hit, Mr. McCovey later said — directly at second baseman Bobby Richardson, who made the grab to secure the championship for the Yankees. It remains one of the most dramatic World Series endings in history.

“One foot higher, or either way,” Mr. McCovey said after the game, “and I guess I would have been a hero.”

He played until 1980 without reaching the World Series again.

Mr. McCovey, who stood tall at the plate and had a majestic swing, was named to six all-star teams and led the league in home runs three times. During the so-called “year of the pitcher” in 1968, he led the National League with 36 home runs and 105 RBIs.

The next year, he was even better, with a league-leading 45 homers and 126 RBIs — both career highs — and a batting average of .320. He was named the league’s Most Valuable Player that year and also won MVP honors at the 1969 All-Star Game in Washington, where he belted two home runs.

Cincinnati Reds pitcher Jim Maloney called Mr. McCovey “the most feared left-handed hitter in the National League.”

After his stellar rookie season in 1959, Mr. McCovey slumped the next year and then played for managers who failed to make the best use of his talent. For several years, Mr. McCovey was in platoons with other players, appearing only against right-handed pitchers.

A natural first baseman, Mr. McCovey had to learn to play the outfield to allow another Giants star, Orlando Cepeda, to remain at first. Along with Mays, the Giants’ dynamic center fielder, they formed the nucleus of the baseball’s most formidable lineups of the 1960s. All three were named to the Hall of Fame, as was the team’s star pitcher, Juan Marichal.

During the 1970s, Mr. McCovey spent three years with the San Diego Padres and Oakland A’s before returning to the Giants for his final four seasons. He was named the NL’s Comeback Player of the Year in 1977, and the Giants retired his number, 44, during his final season in 1980. He entered the Hall of Fame in 1986, the first year he was eligible.

Willie Lee McCovey was born Jan. 10, 1938, in Mobile, Ala., one of 10 children. His father was a railroad worker.

Mr. McCovey followed in a long line of outstanding African American players from Mobile, including Negro leagues pitcher Satchel Paige and Mr. McCovey’s Hall of Fame contemporaries, Aaron and Billy Williams.

He signed his first professional contract at 17 and forced his way into the big leagues at 21 with his prodigious hitting. A knee injury suffered in the minor leagues, however, slowed his running and hampered his career.

His marriage to Karen Billingsley ended in divorce. Survivors include his wife since August, Estela Bejar of Woodside, Calif.; a daughter from his first marriage; a sister; two brothers; and three grandchildren.”

Mr. McCovey endured as one of San Francisco’s most popular players and worked for the Giants for many years as a goodwill ambassador.

“San Francisco is identified with certain things — the bridges, the fog, the cable cars,” he told Sports Illustrated in 1980. “Without bragging, I feel I’ve gotten to the place where people are thinking of me along those lines. I’d like to think that when people think of San Francisco they also think of Willie McCovey.”

In 2000, the Giants opened a new stadium on the edge of San Francisco Bay. Home runs hit especially deep to right field sometimes leave the stadium and splash down in a portion of the bay known as McCovey Cove.