The "Battle of Candlestick", also called the "Battle of San Francisco" or simply the "Marichal–Roseboro brawl", was an infamous bench-clearing brawl which took place on August 22, 1965, at Candlestick Park in San Francisco, California, United States. In what is considered to be one of the most violent on-field brawls in sports history, pitcher Juan Marichal of the San Francisco Giants hit catcher John Roseboro of the Los Angeles Dodgers on the head with a bat, opening a gash on Roseboro's head and starting a fourteen-minute brawl between the teams in the middle of a heated pennant race.

The brawl had short-term and long-term consequences. Marichal's subsequent suspension likely contributed to the Giants losing the pennant race that season. He received a then-record fine, also paying a financial settlement. Due to the incident, Marichal failed to get elected on his first two ballots to the Baseball Hall of Fame. However, Roseboro and Marichal later reconciled, eventually becoming close friends. Roseboro would later lobby to get Marichal elected to the Hall of Fame, while Marichal would later become a pallbearer at Roseboro's funeral.

The 1965 National League pennant chase was a close and heated contest between the Dodgers and the Giants, who had shared an intense rivalry dating back to their days in New York City that carried over after their move to the West Coast. The Milwaukee Braves, Pittsburgh Pirates, and Cincinnati Reds were also involved.

Entering the August 22 game against San Francisco, Los Angeles was in first place in the National League with a 72–52 record, leading the Braves by half a game and the Giants by one and a half games. The game took place in a tense atmosphere, as emotions were raw due to previous minor altercations between the teams. Additionally, the game took place in the aftermath of the Watts riots near the home of Dodger catcher Roseboro, and during the Dominican Civil War raging in the home country of Giants pitcher Marichal.

The game featured a pitching matchup between two aces and future Hall of Famers: Marichal for the Giants and Sandy Koufax for the Dodgers, both favorites to win the Cy Young Award that season. It drew a sold-out crowd at San Francisco's Candlestick Park.

Los Angeles shortstop Maury Wills led off the game with a bunt single off Marichal, and eventually scored a run when Ron Fairly hit a double. Marichal, a fierce competitor, viewed the bunt as a cheap way to get on base and took umbrage with Wills. When Wills came to bat in the second inning, Marichal threw a brushback pitch at him, sending him sprawling to the ground. Willie Mays then led off the bottom of the second inning for the Giants, and Koufax threw a pitch over Mays' head as a token form of retaliation. In the top of the third inning with two outs, Marichal threw a fastball that came close to hitting Fairly, prompting him to dive to the ground. Marichal's act angered the Dodgers sitting in the dugout, and home plate umpire Shag Crawford warned both teams that any further retaliation would not be tolerated.

Marichal himself came up to bat in the third inning, expecting Koufax to retaliate further against him. Instead, he was startled when Roseboro's return throw to Koufax after the second pitch either brushed his ear or came close enough for him to feel the breeze off the ball. When Marichal confronted Roseboro about the proximity of his throw, Roseboro came out of his crouch with his fists clenched. Marichal afterwards stated that he thought Roseboro was about to attack him and raised his bat, striking Roseboro at least twice over the head with it, opening a two-inch gash that sent blood flowing down the catcher's face and required fourteen stitches.

Koufax raced in from the mound attempting to separate the two and was joined by the umpires, players, and coaches from both teams. A fourteen-minute brawl ensued on the field before Koufax, Mays, and other peacemakers restored order. Marichal was ejected from the game and Roseboro was taken to the clubhouse for medical treatment.