Frank Seiler Butterworth Sr. (September 21, 1870 – August 21, 1950)^[1] was an American football player and coach. Butterworth attended Yale University, where he was a fullback on Yale's football teams and a member of the Skull and Bones society.^[1] He was famously enucleated by Bert Waters during "The Bloodbath in Hampden Park". He was selected as an All-American in 1893 and 1894. Butterworth was also a track star and boxer at Yale.^[2] After his college career was over, Butterworth coached football at the University of California, Berkeley (1895–1896) and Yale (1897–1898).^[3] The 1897 Yale football team coached by Butterworth went undefeated with two ties, against Army and Harvard.^[2]

Butterworth worked for the bankers Bertron & Storrs, was a senior partner with real estate brokers F. S. Butterworth & Company, and was president of the New Haven Hotel Company. He served as a Connecticut State Senator from 1907 to 1909 and was a Second Lieutenant in the Chemical Warfare Service during World War I.^[1] Butterworth died in his sleep at age 79 in Connecticut.