January 12 – Boston Red Sox star Ted Williams receives his discharge from the U.S. Marine Air Corps after a three-year stint serving in World War II. In spite of the long absence from competitive baseball, Williams will return to the major leagues by hitting .342 with 38 home runs and 123 RBI in 1946.
January 12 – The first official professional game is played in Venezuela, launching the newly constituted four-team Liga de Béisbol Profesional de Venezuela. The league is composed of four teams: Cervecería Caracas, Magallanes, Vargas and Venezuela. The inaugural game is won by Magallanes over Venezuela, 5–2, behind strong pitching from Alex Carrasquel, who gives up 11 hits in a complete game effort.
February 19 – New York Giants OF Danny Gardella becomes the first major leaguer to announce he is jumping to the "outlaw" Mexican League, the first shot in the series of events that will dominate baseball even more than the return of all the war veterans. His attempt to return to Major League Baseball a few years later will initiate a major court battle.
July 14 – Player-manager Lou Boudreau of the Cleveland Indians hits four doubles and one home run, but Ted Williams wallops three homers and drives in eight runs, as the Boston Red Sox top the Indians, 11–10. In the Sox second-game win, the famous Boudreau Shift is born. Boudreau shifts all his players, except the third baseman and left fielder, to the right side of the diamond in an effort to stop Williams. Ted grounds out and walks twice while ignoring the shift.
March 28 – Chick Fullis, 42, center fielder who played from 1928 to 1936 for the New York Giants, Philadelphia Phillies and St. Louis Cardinals, and a member of the 1934 World Champions Cardinals.
March 28 – Cumberland Posey, 55, Hall of Fame outfielder, manager, executive, and the principal owner of the Homestead Grays, who built a strong barnstorming circuit that made the Grays a perennially powerful and profitable team, one of the best in Negro League history.
April 1 – George Strief, 89, utility man who played all infield and outfield positions for several clubs between 1879 and 1885.
April 4 – Harry Cross, 64, one of the most accomplished sports journalist in New York City for more than three decades.
April 5 – Wally Rehg, 57, right fielder for the Boston Red Sox, Boston Braves and Cincinnati Reds between 1912 and 1919, later a minor league player and manager from 1910 to 1930
April 13 – Billy Gumbert, 80, pitcher who played for the Pittsburgh Alleghenys/Pirates and Louisville Colonels in part of three seasons spanning 1890–1893.
April 15 – Pete Allen, 77, backup catcher for the Cleveland Spiders in the 1893 season.
April 17 – Jack Quinn, 62, Hungarian pitcher who won 247 games with eight different teams from 1909 to 1933, winning his last game when he was 50 years old; setting a record as the oldest Major League pitcher to win a game until Jamie Moyer broke it on April 17, 2012.
April 24 – Joe Birmingham, 61, center fielder and manager for the Cleveland Naps in the early 1900s.
May 6 – Bill Deitrick, 44, outfielder and shortstop for the Philadelphia Phillies in 1927 and 1928.
May 7 – Bill Fincher, 51, pitcher for the 1916 St. Louis Browns of the American League.
May 7 – Bill Fox, 74, second baseman for the Washington Senators in 1897 and the Cincinnati Reds in 1901, who also spent 13 seasons in the Minor Leagues as a player/manager between 1894 and 1915.
May 10 – Harry Swan, 58, who made one pitching appearance for the Kansas City Packers of the Federal League in 1914.
May 15 – Ed Mayer, 80, third baseman in 188 games for the Philadelphia Phillies from 1890 to 1891.
May 19 – John K. Tener, 82, Irish pitcher and outfielder who played from 1888 through 1890 for the Baltimore Orioles, Chicago White Stockings, and Pittsburgh Burghers before becoming president of the National League from 1913 to 1918.
May 22 – Harry Betts, 64, who pitched one game in 1903 with the St. Louis Cardinals, and then came back to the majors ten years later in 1913 to pitch one more game for the Cincinnati Reds in 1913.
May 23 – Johnny Grabowski, 46, catcher who played for three teams in a span of seven seasons from 1924–1931, and a member of the Murderers' Row New York Yankees clubs that clinched the World Series in 1927 and 1928.
May 30 – Billy Earle, 78, catcher for five major league teams in five seasons from 1889–1894, who continued playing and managing in the minors until 1906, and also managed the Almendares BBC in 1901 to become the first American manager in Cuban Winter League history.
August 6 – Tony Lazzeri, 42, Hall of Fame and All-Star second baseman for the New York Yankees, who won six American League pennant winners from 1926 through 1937, while batting .300 five times and collecting seven 100-RBI seasons, including two grand slams and 11 RBI in a 1936 game, and a .400 average in the 1937 World Series.
November 3 – Ben Taylor, 57, pitcher for the 1912 Cincinnati Reds.
November 4 – John Barthold, 64, pitcher who played for the Philadelphia Athletics during the 1904 season.
November 5 - Alejandro Oms, 51, Cuban center fielder who played in the Negro Leagues.
November 7 – Tom Daly, 54, Canadian catcher for the Chicago White Sox, Cleveland Indians and Chicago Cubs during eight seasons spanning 1913–1921, who later managed the Toronto Maple Leafs of the International League, and coached for the Boston Red Sox in 14 seasons (1933–1946), to set the longest consecutive-year coaching tenure in Bosox history.
November 11 – Art Reinhart, 47, pitcher who played for the St. Louis Cardinals in a span of five seasons from 1919 to 1928.
November 18 – Johnny Lush, 61, pitcher for the Philadelphia Phillies and St. Louis Cardinals from 1904 through 1910, who no-hit the Brooklyn Superbas in 1906, which was the last no-hitter by a Phillies pitcher in 57 years until Jim Bunning hurled a perfect game in 1964.
November 27 – Arlie Tarbert, 42, reserve outfielder for the 1927–1928 Boston Red Sox.
December 10 – Walter Johnson, 59, Hall of Fame pitcher who played from 1907 through 1927 for the Washington Senators, whose 417 career victories ranks second to the 511 achieved by Cy Young, while setting an all-time record with 110 shutouts, and collecting 3,509 strikeouts, twelve 20-win seasons, including two 30-win seasons, as well as eleven seasons with an earned run average below 2.00, 5,914 innings pitched, and 531 complete games in 666 starts.
December 10 – Walter Moser, 65, pitcher for the Philadelphia Athletics, Boston Red Sox and St. Louis Browns in a span of three seasons from 1906–1911.
December 10 – Damon Runyon, 62, famed New York sportswriter and author.
December 14 – Tom Dowse, 80, Irish catcher/outfielder who played in the 1890s for the Cleveland Spiders/Solons, Louisville Colonels, Cincinnati Reds, Philadelphia Phillies and Washington Senators.
December 21 – Bill Evans, 53, pitcher for the Pittsburgh Pirates in three seasons from 1916–1919.
December 30 – Pat McGehee, pitcher who played for the 1912 Detroit Tigers.