Melvin Frederick Nelson (May 30, 1936 – November 26, 2021) is a retired American professional baseball player and scout. A left-handed pitcher, the native of San Diego, California, appeared in 93 games, 82 in relief, over six seasons in Major League Baseball for the St. Louis Cardinals, Los Angeles Angels and Minnesota Twins. He was listed as tall and .
Nelson's 15-year playing career included the entire season and parts of five others in the Major Leagues. In 1965, he appeared in 28 games and 54 innings pitched for the American League champion Twins and was winless in four decisions with three saves. However, he did not pitch in the 1965 World Series. Three years later, in his second stint with the Cardinals, Nelson—recalled from the minor leagues in midyear—contributed two wins to the Redbirds' pennant-winning season, both as a starting pitcher. He then appeared in the 1968 World Series in a "mop-up" role in Game 6, hurling a scoreless ninth inning in a game won by the opposing Detroit Tigers, 13–1.
During his big-league career, Nelson allowed 184 hits and 69 bases on balls in 173 innings pitched, recording 98 strikeouts and five saves. He handled 40 total chances (7 putouts, 33 assists) without an error for a perfect 1.000 fielding percentage.
After retiring from the field, Nelson then scouted for the Cardinals and other MLB clubs. Nelson died November 26, 2021, in Highland, California.