William P. Fleckenstein (November 4, 1903 - January 1967) was a professional American football player who played offensive lineman for seven seasons for the Chicago Bears, the Portsmouth Spartans, the Brooklyn Dodgers, and the Frankford Yellow Jackets. In March 1934, he married the actress Mildred Harris, previously married to Charlie Chaplin, with whom he lived until her death in 1944.