Although the Negro American League would last until 1960, 1951 was, notably, the last season in which the Negro American League was considered major-league caliber, which was itself the last major Negro league baseball organization.
March 21 – During spring training, Pittsburgh Pirates lefty first baseman Dale Long makes his first appearance as a catcher in an exhibition game at San Diego, California, after Pirates general manager Branch Rickey decided to flaunt tradition and try him as a catcher for the foreseeable future. Pretty soon, Long joined the St. Louis Browns on waivers and went back to first base. Eventually, he would caught two games in 1958 with the Chicago Cubs, using a first baseman's mitt.
July 28 – Clyde Vollmer, who started the month on the bench, continues his explosive fireworks against the Indians. Vollmer singles in the tying run in the 15th inning and then in the 16th hits a grand slam off reliever Bob Feller for an 8-4 Red Sox win. The grand slam is the latest hit in a game in major-league history. Mickey McDermott pitches all 16 innings for the Sox, striking out 15 and walking one.
August 19 – Bill Veeck, the showman and maverick owner of the St. Louis Browns, pulls off one of the greatest stunts in baseball history. In the second game of a doubleheader against the Detroit Tigers, Veeck sends Eddie Gaedel to the plate as a pinch-hitter for leadoff batter Frank Saucier. At 3 feet 7 inches (1.09 m) tall, Gaedel became the shortest player in baseball history. Due to his extremely small strike zone, Gaedel walked on four consecutive pitches and was immediately pulled for a pinch-runner. American League president Will Harridge, saying Veeck was making a mockery of the game, voided Gaedel's contract the next day. Detroit went on to win the game, 6-2.
October 3 – The New York Giants had been thirteen and one-half games behind the National League leading Brooklyn Dodgers in August, but under Leo Durocher's guidance and with the aid of a sixteen-game winning streak, caught the Dodgers to tie for the lead with two days left in the season. As both teams won their last two games, they ended up tied. The two teams play a best-of three playoff. In Game 3 with one out in the ninth inning and runners on second and third, the Giants were down 4-2 to the Dodgers when Bobby Thomson hit a home run to win the game 5-4. The "Shot heard 'round the world" clinched the National League pennant for the Giants, and WMCA-AM radio announcer Russ Hodges' frantic "The Giants win the pennant!", said four times consecutively, is one of the most famous home run calls in baseball history.
November 10 – In Tokyo, Japan 50,000 fans are on hand as an American All-Star team battles a Central League All-Star team. Joe DiMaggio hits a 400 foot home run in the eighth inning to tie the game at 1–1, then his younger brother Dom laces an RBI-triple in the ninth and later scores to give the Americans a 3–2 victory. The Americans have won 12 games and tied one.
January 6 – Harry Camnitz, 66, pitcher who played with the Pittsburgh Pirates in the 1909 season and for the St. Louis Cardinals in 1911.
January 10 – Tom Delahanty, 78, third baseman for the Philadelphia Phillies, Cleveland Spiders, Pittsburgh Pirates and Louisville Colonels of the National League in a span of three seasons between 1894 and 1897.
January 11 – Bill Wagner, 57, catcher who played from 1914 through 1918 for the Pittsburgh Pirates and Boston Braves.
January 16 – Pid Purdy, 46, two-sport athlete who played outfield in four Major League seasons with the Chicago White Sox and Cincinnati Reds from 1927 to 1929, and was a quarterback in the National Football League for the Green Bay Packers in 1926 and 1927.
January 26 – Bill Barrett, 50, outfielder who played for the Philadelphia Athletics, Chicago White Sox, Boston Red Sox and Washington Senators over nine seasons between 1921 and 1930.
February 2 – Bill Sowders, 86, pitcher who played from 1888 through 1890 for the Boston Beaneaters and Pittsburg Alleghenys clubs of the National League.
February 6 – Gabby Street, 68, whose baseball career came into prominence as the personal catcher for the legendary pitcher Walter Johnson with the Washington Senators, while being the first man to catch a baseball dropped from the top of Washington Monument, and also known as one of the few Major League managers to capture a World Series title in his first intent, as he did with the St. Louis Cardinals in 1930.
February 8 – Harry Ables, 67, pitcher who played for the St. Louis Browns, Cleveland Naps and New York Highlanders in part of three seasons spanning 1905–1911.
February 14 – Harry Thompson, 61, pitcher who split his only big-league season between the Washington Senators and the Philadelphia Athletics in 1919.
February 20 – Marty Shay, 54, infielder who played with the Chicago Cubs in the 1916 season and for the Boston Braves in 1924.
March 3 – Dan Bickham, 86, pitcher who played in 1886 for the Cincinnati Red Stockings of the National League.
March 13 – Joe Hughes, 71, backup outfielder for the 1902 Chicago Orphans of the National League.
March 20 – Roscoe Coughlin, 83, pitcher who played from 1890 to 1891 for the Chicago Colts and New York Giants.
March 25 – Eddie Collins, 63, Hall of Fame second baseman who played from 1906 through 1930 for the Philadelphia Athletics and Chicago White Sox, won the American League MVP Award in 1914, also managed the White Sox in 1926 and 1927, and is the only AL player to steal six bases in a single game; a feat he accomplished twice in September 1912, while leading the Athletics to four American AL pennants and three World Series championships between 1910 and 1914 as well as the White Sox to the 1917 World Series title, while ending his career with a .333 average, .424 on-base percentage, 3,314 hits, and 745 stolen bases in 2,826 games.
March 25 – Dan Daub, 83, pitcher who played in 1892 with the Cincinnati Reds and for the Brooklyn Grooms and Bridegrooms clubs from 1893 through 1897.
March 28 – Kohly Miller, 77, backup infielder who played for the Washington Senators, St. Louis Browns and Philadelphia Phillies in a span of two seasons between 1892 and 1897.
April 14 – Danny Moeller, 66, outfielder for the Pittsburgh Pirates, Washington Senators and Cleveland Indians during seven seasons between 1907 and 1916, who is listed as the first big leaguer of the dead-ball era (before 1950) to have at least five home runs and 100-plus strikeouts in consecutive seasons (1912–1913).
April 20 – Roy Brashear, 77, backup infielder for the St. Louis Cardinals and Philadelphia Phillies in part of two seasons from 1902–1903, who later umpired in the Pacific Coast League for several years.
April 22 – Ox Eckhardt, 49, right fielder who played with the Boston Braves in the 1932 season and for the Brooklyn Dodgers in 1936.
April 27 – Bill Eagle, 73, outfielder who played in 1898 for the Washington Senators of the National League.
June 11 – Tom Leahy, 82, backup catcher who played with five different teams in a span of five seasons from 1897–1905, mostly for the Washington Senators of the National League between 1897 and 1898.
June 17 – Bill Harper, 62, pitcher who appeared in two games for the St. Louis Browns of the American League in its 1911 season.
June 19 – Wally Gerber, 59, a slick shortstop with good hands and a strong throwing arm, who played for the Pittsburgh Pirates, St. Louis Browns and Boston Red Sox over 15 seasons between 1914 and 1929, while setting a Major League record for shortstops with 48 fielding chances in four consecutive games during the 1923 season, and leading the American League in double plays in 1920 and from 1926 to 1927.
July 3 – Hugh Casey, 37, relief pitching ace for the Brooklyn Dodgers in the 1940s, whose best season came in 1947 when he won 10 games and led the National League with 18 saves, establishing later a World Series record while facing the New York Yankees in six of the seven games of the Series, five consecutively, being credited with a 2-0 record, one save and only one run in 10⅓ innings of work.
July 6 – Ted Easterly, 66, catcher for the Cleveland Naps, Chicago White Sox and Kansas City Packers in a span of six seasons from 1909 to 1915, who posted a batting average over .300 over three consecutive seasons with a career-high .324 in 1911, ranking twice among the top ten hitters in the American League and once in the Federal League.
July 9 – Harry Heilmann, 56, Hall of Fame outfielder and Detroit Tigers star, who won four batting titles in the American League between 1921 and 1927, compiling averages of .394, .403, .393 and .398, whose career .342 batting average ranks him 12th in the all-time list.
July 9 – Huck Wallace, 68, pitcher for the 1912 Philadelphia Phillies.
July 10 – Bobby Messenger, 67, outfielder who played with the Chicago White Sox and St. Louis Browns in part of four seasons between 1909 and 1914.
July 14 – Dee Cousineau, 52, catcher who played for the Boston Braves in three seasons from 1923 to 1925.
July 14 – Vance Page, 45, pitcher who spent four seasons with the Chicago Cubs from 1938 through 1941.
July 18 – Joe Klugmann, 56, second baseman who played for the Chicago Cubs, Brooklyn Robins and Cleveland Indians in part of four seasons between 1921 and 1925.
August 1 – Harry Curtis, 68, catcher for the 1907 New York Giants.
August 2 – Guy Cooper, 68, pitcher who played from 1914 to 1915 for the New York Yankees and Boston Red Sox.
August 4 – Tony Tonneman, 69, catcher who played briefly for the 1911 Boston Red Sox.
August 7 – Bill Wynne, 82, who pitched in 1894 with the Washington Senators of the National League.
August 7 – Biff Wysong, 46, pitcher who played from 1930 through 1932 for the Cincinnati Reds.
August 10 – Win Kellum, 75, Canadian pitcher for the Boston Americans, Cincinnati Reds and St. Louis Cardinals during three seasons 1901 and 1905, who in 1901 became the first Opening Day starting pitcher in Boston American League franchise's history.
August 12 – Paul McSweeney, 84, backup infielder who appeared in three games for the 1891 St. Louis Browns of the National League.
August 17 – Doc Crandall, 63, pitcher who played with six teams in three diferent leagues between 1908 and 1918, most prominently for the New York Giants from 1908 to 1913, playing for them in three consecutive World Series from 1911–1913 and known also for his hitting, as he was often used as a pinch-hitter by Giants manager John McGraw.
August 17 – Ren Wylie, 89, center fielder who appeared in just one game for the 1882 Pittsburg Alleghenys.
August 19 – Ollie Hanson, 55, pitcher who played for the Chicago Cubs in its 1921 season.
August 28 – Billy Lush, 77, very solid center fielder who spent seven seasons in the majors with four teams from 1895–1904, enjoying his most productive seasons in 1903 and 1904 with the Detroit Tigers and Cleveland Naps, respectively.
August 28 – Bill Piercy, 55, pitcher who played for the New York Yankees, Boston Red Sox and Chicago Cubs during six seasons between 1917 and 1926, including the Yankees team that won the 1921 American League pennant.
September 4 – Carl Doyle, 39, pitcher who spent four seasons between 1935 and 1940 with the Philadelphia Athletics, Brooklyn Dodgers and St. Louis Cardinals.
September 5 – Jim Keesey, 48, first baseman who played with the Philaldelphia Athletics in part of two seasons spanning 1925–1930.
September 9 – Chappie Snodgrass, 81, backup outfielder for the 1901 Baltimore Orioles.
September 10 – Hank DeBerry, 56, catcher who played for the Cleveland Indians and Brooklyn Robins in a span of eleven seasons from 1916–1930.
September 12 – Lave Winham, 69, who pitched from 1902 to 1903 for the Brooklyn Superbas and Pittsburgh Pirates.
September 14 – Wally Roettger, 49, outfielder for the St. Louis Cardinals, Cincinnati Reds, New York Giants and Pittsburgh Pirates from 1927 through 1935, who got the first hit and scored the first run in Game 1 of the 1931 World Series for the eventual champion Cardinals.
September 16 – Bill Klem, 77, Hall of Fame umpire known as the Old Arbitrator and the Father of Baseball Umpires, who officiated National League games during a 37-year career from 1905 to 1941 and introduced the inside chest protector, while working in 18 World Series to set a Major League Baseball record for umpires.
September 23 – Dale Gear, 79, who pitched with the Cleveland Spiders in the 1896 season and for the Washington Senators in 1901.
September 25 – Nolen Richardson, 48, third baseman for the Detroit Tigers, New York Yankees and Cincinnati Reds during six seasons between 1929 and 1939, who also was the shortstop and captain of the 1937 Newark Bears, which is widely regarded as the best in Minor League Baseball history.
October 11 – Bob Becker, 76, pitcher for the Philadelphia Phillies in the 1897 and 1898 seasons.
October 12 – Bill Essick, 70, pitcher for the Cincinnati Reds from 1906 to 1907 and later a longtime Minor League manager and New York Yankees scout, who is credited for discovering or signing future Yankees stars Joe DiMaggio, Lefty Gomez, Joe Gordon and Ralph Houk, among others.
October 12 – Pug Griffin, 55, utility outfielder for the Philadelphia Athletics in 1917 and the New York Giants in 1920, who later became a successfully manager in the Minor Leagues, guiding the Lincoln Links to the 1943 Nebraska State League title, and the Pueblo Rollers to the Western League championship in 1941.
October 12 – Rube Vinson, 72, outfielder who played from 1904 through 1906 for the Cleveland Naps and Chicago White Sox.
October 14 – Henry Zeiher, 89, catcher for the 1886 Washington Nationals of the National League.
October 17 – Al Clancy, 63, third baseman who appeared in three games for the St. Louis Browns in its 1911 season.
October 19 – Emil Haberer, 73, catcher and corner infielder who played for the Cincinnati Reds in a span of three seasons from 1901–1909.
October 27 – Pryor McElveen, 69, third baseman who played for the Brooklyn Superbas and Dodgers teams between 1909 and 1911.
October 27 – John Brock, 55, backup catcher for the St. Louis Cardinals in the 1917 and 1918 seasons.
October 30 – Walt Woods, 76, valuable utility man who played all positions except catcher and first base, whose career included stints with the Chicago Orphans, Louisville Colonels and Pttsburgh Pirates during three seasons from 1898 to 1900.
November 1 – Mickey Doolin, 71, slick fielding shortstop who played for the Philadelphia Phillies, Chicago Whales, Chicago Cubs, New York Giants and Brooklyn Robins in a span of 13 seasons between 1905 and 1918, while leading the National League in putouts four times, assists five times, double plays five times, and fielding percentage once.
November 3 – Joe Hovlik, 67, Hungarian pitcher who played from 1909 to 1911 for the Chicago White Sox and Washington Senators.
November 5 – George Stovall, 73, who played and managed from 1904 through 1913 for the Cleveland Naps and St. Louis Browns of the American League, and for the Kansas City Packers of the outlaw Federal League in 1914 and 1915.
November 6 – Carl Husta, 49, shortstop who appeared in six games with the 1925 Philadelphia Athletics.
November 8 – Claude Ritchey, 78, middle infielder and outfielder over 13 seasons for the Cincinnati Reds, Pittsburgh Pirates, Boston Doves and Louisville Colonels, who helped the Pirates win three consecutive National League pennants from 1901 to 1903.
November 11 – Jim Neher, 62, pitcher who appeared in just one game for the Cleveland Naps in their 1912 season.
November 18 – Wally Mayer, 61, catcher who played from 1911 through 1919 for the Chicago White Sox, Boston Red Sox and St. Louis Browns.
November 19 – Marty Griffin, 50, pitcher for the 1928 Boston Red Sox.
November 19 – Crese Heismann, 71, pitcher who played from 1901 to 1902 with the Cincinnati Reds and Baltimore Orioles.
November 20 – Fred Burchell, 72, who pitched with the Philadelphia Phillies during the 1903 season and for the Boston Americans and Red Sox from 1907 to 1909.
November 20 – Joe Rogalski, 39, pitcher who played in 1938 with the Detroit Tigers.
November 26 – Pete Hill, 71, Hall of Fame outfielder whose career from 1889 to the mid-1920s involved some of the pioneer programs of the Negro Leagues, being considered to be a great center fielder with a strong arm and excellent glove, while his talents also extended as a consistent line-drive hitter, both for average and power, with outstanding speed on the base paths, closing his career by serving as the player-manager for several teams between 1914 and 1925.
December 5 – Jim Duggan, 66, first baseman who played for the St. Louis Browns in its 1911 season.
December 5 – Shoeless Joe Jackson, 63, left fielder and prominent hitter whose career lasted from 1908 to 1920 with the Philadelphia Athletics, Cleveland Naps and Chicago White Sox, who hit .408 in 1908, the highest batting average ever by a rookie, while hitting a slash line of .408/.468/.590 in 1911 during his first season as a full-time player, and leading the White Sox to the 1917 World Series victory against the New York Giants, ending his career with a .356 average for the third highest in Major League history, before being banished from the sport for his involvement in the Black Sox scandal.
December 18 – Joe Ohl, 63, pitcher for the 1909 Washington Senators.
December 19 – Bob Lindemann, 70, backup outfielder who played for the Philadelphia Athletics in 1901.
December 27 – Ernie Lindemann, 73, pitcher who appeared in one game for the Boston Doves in 1907.
December 29 – Hiram Bithorn, 35, pitcher who was the first player born in Puerto Rico to play in the Major Leagues when he made his debut with the Chicago Cubs in its 1942 season, leading the National League pitchers with seven shutouts in 1943, while posting a record of 34–31 and 3.16 ERA in 105 games over four seasons.
December 30 – Bob Kinsella, 52, outfielder who spent two seasons with the New York Giants from 1919 to 1920.