William Collazo [koy-yah'-zo] (born November 7, 1979) is a Puerto Rican former professional baseball pitcher.

During the 2007 season, he appeared in six games for the New York Mets of Major League Baseball (MLB).

Since 2016, Collazo has worked as a minor league pitching coach in the Toronto Blue Jays organization.

Collazo graduated from Florida International University, where he went 13–1 as a senior and helped his team to the NCAA Division I Baseball Championship tournament.

He became a free agent at the end of the 2008 season and signed a minor league contract with the Florida Marlins.