The New York Giants were a Major League Baseball team in the National League that began play in the 1883 season as the New York Gothams and became known as the Giants in 1885. They continued as the New York Giants until the team moved to San Francisco after the 1957 season, where the team continues its history as the San Francisco Giants. The team moved west at the same time as its longtime rival, the Brooklyn Dodgers, also in the National League, moved to Los Angeles in Southern California as the Los Angeles Dodgers, continuing the National League, same-state rivalry.

During most of their 75 seasons in New York City, the Giants played home games at various incarnations of the Polo Grounds in Upper Manhattan. Numerous inductees of the National Baseball Hall of Fame and Museum played for the New York Giants, including Christy Mathewson (a member of the Hall of Fame's inaugural class), John McGraw, Mel Ott, Bill Terry, Willie Mays, Monte Irvin, Frankie Frisch, Ross Youngs and Travis Jackson. During the club's tenure in New York, it won five of the franchise's eight World Series championships and 17 of its 23 National League pennants. Famous moments in the Giants' New York history include the 1922 World Series, in which the Giants swept the Yankees in four games, Bobby Thomson's 1951 home run known as the "Shot Heard 'Round the World", and the defensive feat by Willie Mays during the first game of the 1954 World Series known as "the Catch".

The Giants had intense rivalries with their fellow New York teams the New York Yankees and the Brooklyn Dodgers, facing the Yankees in six World Series and playing the league rival Dodgers multiple times per season. Games between any two of these three teams were known collectively as the Subway Series.

The New York Giants of the National Football League were named after the team; to distinguish the two clubs, the football team was legally incorporated as the New York Football Giants, which remains its corporate name to this day.

The New York Giants had an overall win–loss record of 6,067–4,898–157 (.553) during their 74 years in New York. Nineteen former New York Giants players were elected to the National Baseball Hall of Fame.

The Giants began as the second baseball club founded by millionaire tobacconist John B. Day and veteran amateur baseball player Jim Mutrie. The Gothams, as the Giants were originally known, entered the National League seven years after its 1876 formation, in 1883, while their other club, the Metropolitans played in the rival American Association (1882–1891). Nearly half of the original Gothams players were members of the disbanded Troy Trojans in upstate New York, whose place in the National League the Gothams inherited. While the Metropolitans were initially the more successful club, after they won the 1884 AA championship, Day and Mutrie began moving star players to the NL Gothams, whose fortunes improved while the Metropolitans' afterwards slumped.

It is said that after one particularly satisfying victory over the Philadelphia Phillies, Mutrie (who was also the team's manager) stormed into the dressing room and exclaimed, "My big fellows! My giants!" From then on (1885), the club was known as the Giants. However, more recent research has suggested that the New York World was already widely using the Giants nickname throughout the 1885 season, before the legendary game was played.

The team won its first National League pennant in 1888, as well as a victory over the St. Louis Browns in an early incarnation of the pre-modern-era World Series. They repeated as champions the next year with a pennant and world championship victory over Brooklyn.