Guillermo Díaz (born March 4, 1985) is a Puerto Rican professional basketball player who plays for Cangrejeros de Santurce of the Baloncesto Superior Nacional (BSN). Díaz was drafted by the Los Angeles Clippers of the National Basketball Association (NBA) in 2006, becoming the fifth Puerto Rican ever drafted by the NBA and the eighth to play there. He has also played professionally in Europe and in Puerto Rico.