Guillermo "Willie" Hernández Villanueva (born November 14, 1954) is a former relief pitcher for the Chicago Cubs (1977–1983), Philadelphia Phillies (1983), and Detroit Tigers (1984–1989).
He threw and batted left-handed.
Hernández utilized the screwball.In 1984, Hernandez became only the third player ever to win the Cy Young Award, the MVP Award, and the World Series title all in the same season (Sandy Koufax was the first to accomplish this feat, in 1963 and Denny McLain did it in 1968.)