Elmer Jay Rieger (February 25, 1889 – October 21, 1959), was a Major League Baseball pitcher who played in 1910 with the St. Louis Cardinals. He batted right and left and threw right-handed. Rieger had a 0–2 record, with a 5.48 ERA, in 13 games, in his one-year career.
He was born in Perris, California and died in Los Angeles, California.