James Arthur "Rube" Parnham (February 1, 1894 – November 25, 1963) was an American Major League Baseball pitcher for the 1916 and 1917 Philadelphia Athletics.

He led the league in wins (28) and strikeouts (187), as the Orioles dynasty won their first pennant.

After starting out 5–0 in 1920, Parnham quit the team in 1920 to pitch in a Pennsylvania industrial league.

He managed to outshine even future Hall of Famer Lefty Grove, who was on the same team.

Ever unpredictable, Parnham quit the team again the following season and pitched his last professional game in 1927.