David Leonard Brain (January 24, 1879 – May 25, 1959) was an infielder/outfielder in Major League Baseball who played for the Chicago White Sox (1901), St. Louis Cardinals (1903–1905), Pittsburgh Pirates (1905), Boston Beaneaters/Doves (1906–1907), Cincinnati Reds (1908) and New York Giants (1908).

Brain was an unreliable fielder who showed some power with his bat and good speed on the basepaths.

In 1903 for the St. Louis Cardinals he stole 21 bases and hit 15 triples, including two three-triple games to become the only player in National League history to perform the feat twice in a season.

In 1904 Brain played around the infield, hitting 24 doubles with 12 triples and 18 stolen bases, and also posted a career-high with 72 runs batted in.

In a seven-season career, Brain was a .252 hitter with 27 home runs and 303 RBI in 679 games.