Patrick Paul Billingsley (May 3, 1925 – April 22, 2011[1][2]) was an American mathematician and stage and screen actor, noted for his books in advanced probability theory and statistics.

He was born and raised in Sioux Falls, South Dakota, and graduated from the United States Naval Academy in 1946.

He was given the Lester R. Ford Award for his article "Prime Numbers and Brownian Motion.

[citation needed] In Young Men and Fire, fellow University of Chicago professor Norman Maclean wrote about Billingsley that "he is a distinguished statistician and one of the best amateur actors I have ever seen".

He was survived by his children, Franny, Patty, Julie, Marty and Paul, and his companion, Florence Weisblatt.