Sidney Gillman (October 26, 1911 – January 3, 2003) was an American football player, coach, executive, and innovator. Gillman's insistence on stretching the football field by throwing deep downfield passes, instead of short passes to running backs or wide receivers at the sides of the line of scrimmage, was instrumental in making football into the modern game that it is today.
Gillman played football as an end at Ohio State University from 1931 to 1933. He played professionally for one season in 1936 with the Cleveland Rams of the second American Football League. After serving as an assistant coach at Ohio State from 1938 to 1940, Gillman was the head football coach at Miami University from 1944 to 1947 and at the University of Cincinnati from 1949 to 1954, compiling a career college football record of 81–19–2. He then moved to the ranks of professional football, where he headed the NFL's Los Angeles Rams (1955–1959), the American Football League's Los Angeles and San Diego Chargers (1960–1969), and the NFL's Chargers (1971), and Houston Oilers (1973–1974), amassing a career record of 123–104–7 in the National Football League and the American Football League. Gillman's 1963 San Diego Chargers won the AFL Championship. Gillman was inducted as a coach into the Pro Football Hall of Fame in 1983 and the College Football Hall of Fame in 1989. He is the sole coach in the history of American football to have earned both honors.