Samuel R. Marsonek (born July 10, 1978) is a former Major League Baseball pitcher. Marsonek was a 1st round pick (24th overall) of the Texas Rangers in the 1996 Major League Baseball Draft. He has appeared in only one major league game in his career, on July 11, 2004, for the New York Yankees. He pitched 11⁄3 scoreless innings in relief.
In 2007, Marsonek pitched in the independent Atlantic League for the Somerset Patriots. In 35 games (14 starts), he was 6-8 with a 5.03 ERA and 59 strikeouts.