Efraín Nieves (born November 15, 1989) is a Puerto Rican professional baseball player. A pitcher, he plays in Minor League Baseball in the organization of the Toronto Blue Jays of Major League Baseball.
Nieves attended the Puerto Rico Baseball Academy. The Milwaukee Brewers drafted Nieves in the seventh round of the 2007 Major League Baseball Draft. He later played in Minor League Baseball for the Detroit Tigers and the Blue Jays.
Nieves played for the Puerto Rican national baseball team in the 2013 World Baseball Classic.