Ralph Grant "Lefty" Caldwell (January 18, 1884 – August 5, 1969) was an American pitcher in Major League Baseball.

He entered the University of Pennsylvania in 1902 and played on the school's baseball team in 1903 and 1904.

[2] Caldwell made his professional baseball debut for the National League's Philadelphia Phillies on September 10, 1904.

[1] During the 1905 season, he also played for the Eastern League's Toronto Maple Leafs.

[3] Caldwell died in West Trenton, New Jersey, in 1969 and was buried in Ewing Church Cemetery.