William Mackrides (July 8, 1925 – January 22, 2019) was an American football quarterback for the Philadelphia Eagles of the National Football League (NFL).
Mackrides played college football for the University of Nevada, Reno and led the nation in passing in 1946.
In his last professional season in 1953, Mackrides played for the Pittsburgh Steelers and was the last Steeler to wear uniform number 13 in a regular season game until punter Jeremy Kapinos wore that number in 2010.
Mackrides later gained degrees (MS and PhD) in education, undergraduate at West Chester State College, a master's degree at the University of Pennsylvania, and a doctorate in psychology at the University of New Mexico.
He also founded Indian Springs Day Camp, a summer day camp in Chester Springs, Pennsylvania, in 1959, which family owned and operated as of 2013.