John Frank "Buck" Freeman (October 30, 1871 – June 25, 1949) was an American right fielder in Major League Baseball at the turn of the 20th century. Listed at 5 ft 9 in (1.75 m) and 169 lb (77 kg), he both batted and threw left-handed. Freeman was one of the top sluggers of his era, his most famous feat being the 25 home runs he hit during the 1899 season.

A native of Catasauqua, Pennsylvania, Freeman showed talent as a pitcher from a young age; he later received advice from early African-American player Bud Fowler to practice hitting more.

Freeman made his major league debut as a left-handed starting pitcher with the Washington Statesmen of the major league American Association on June 27, 1891, registering the loss in a 4–5 defeat to the Philadelphia Athletics. Freeman played in a further four games during the season, finishing up with a 3–2 record and an earned run average of 3.89 in 44 innings pitched, while striking out 28 but also walking 33.

Following the 1891 season's conclusion, Freeman did not play in the majors again for seven years. From 1892 through 1898, he played in the Pennsylvania State League, Eastern League, New England League, and Western League. His longest stint was in the Eastern League with Toronto from 1896 to 1898.

Freeman returned to the Washington roster in September of the 1898 season, when Arthur Irwin took over as manager; the team was now known as the Senators and played in the National League. Since Freeman's time as a pitcher with the Statesmen, he had bulked out and had begun to show real skill with the bat (in his 18 at bats in 1891 he had recorded a batting average of .222). In light of this, the Senators decided to retrain Freeman as a right fielder, believing that he would be even more useful with the bat than he was with the ball. Albeit with only 107 at bats in 29 games, he recorded a .364 batting average and a .523 slugging percentage during the final weeks of the 1898 Senators season. Following his strong showing with the bat, he was named as the Senators' first-choice right fielder for the following season.

The 25 home runs that Freeman recorded for the 1899 Senators were truly remarkable by the standards of the time; the second highest total that year was 12 by Bobby Wallace of St. Louis. Although Freeman failed to equal Ned Williamson's record of 27 home runs in a season, recorded in 1884 with Chicago, Freeman's total is generally regarded as the greater achievement. Williamson's home field of Lakeshore Park was less than 200 feet (61 m) down the foul lines and 300 feet (91 m) to center, and prior to 1884 balls hit over the fence at Lakeshore Park had been ground rule doubles; of Williamson's 27 homers, only two were hit away from home. Freeman's tally was not surpassed until 1919, when Babe Ruth hit 29 home runs with the Boston Red Sox.

Freeman's contract was sold to Boston in February 1900, as Washington owner J. Earl Wagner correctly foresaw that the National League would be reduced in size. The Senators were one of the teams disbanded as the league contracted from twelve teams to eight.

Freeman spent the 1900 season with the Boston Beaneaters (later known as the Boston Braves), where he did not get along with manager Frank Selee. Freeman's offensive numbers for the season were well down from the year before, as he recorded six home runs and 65 runs batted in during 117 games played. On September 1, during a game between Boston and the New York Giants, assigned umpire Ed Smartwood had to leave the game due to injury; the final four innings were completed with Freeman umpiring at home and Bill Carrick of the Giants umpiring at first.