William "Bill" Mackrides (born July 8, 1925) is a former American football quarterback for the Philadelphia Eagles of the National Football League. He helped the Eagles win the 1948 and 1949 NFL Championships. Mackrides played college football for the University of Nevada, Reno and led the nation in passing in 1946. In his last 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 and psychology. He has since retired and, as of 2013, resides in Delaware County, Pennsylvania. He also founded Indian Springs Day Camp, a summer day camp in Chester Springs, Pennsylvania in 1959, which is currently family owned and operated.