People from Monmouth, Illinois

Wyatt Berry Stapp Earp (March 19, 1848 – January 13, 1929) was an American Old West lawman and gambler in Cochise County, Arizona Territory, and a deputy marshal in Tombstone. He worked in a wide variety of trades throughout his life and took part in the famous Gunfight at the O.K. Corral, during which lawmen killed three outlaw Cochise County Cowboys. He is often erroneously regarded as the central figure in the shootout, although his brother Virgil was Tombstone city marshal and deputy U.S. marshal that day and had far more experience as a sheriff, constable, marshal, and soldier in combat.

Rosa Smith Eigenmann (October 7, 1858 – January 12, 1947) was an American ichthyologist (the branch of zoology devoted to the study of fish), as well as a writer, editor, former curator at the California Academy of Sciences, and the first librarian of the San Diego Society of Natural History. She "is considered the first woman ichthyologist in the United States." Eigenmann was also the first woman to become president of Indiana University's chapter of Sigma Xi, an honorary science society. She authored twelve published papers of her own between 1880 and 1893, and collaborated with her husband, Carl H. Eigenmann, as "Eigenmann & Eigenmann" on twenty-five additional works between 1888 and 1893. Together, they are credited with describing about 150 species of fishes.

Gladys Gale (January 15, 1891 – October 4, 1948) was an American nightclub singer and vaudeville performer, before becoming a character actress in films during the 1930s and 1940s. The wife of a millionaire, she led a checkered life before dying under mysterious circumstances in a Los Angeles hotel room under an assumed name.

Philip G. Killey is a retired United States Air Force officer. He attained the rank of Major General, and served as Adjutant General of the South Dakota National Guard, Director of the Air National Guard and Commander of First Air Force.

Francis Louis "Jug" Earp (July 22, 1897 – January 8, 1969) was a professional American football player. He attended Monmouth College in Monmouth, Illinois with the class of 1921. He played 11 seasons in the National Football League (NFL), mostly with the Green Bay Packers and was inducted into the Green Bay Packers Hall of Fame in 1970. He also played with the Rock Island Independents, three games for the New York Yankees, and one game for the Frankford Yellow Jackets.

J. P. Machado (born January 6, 1976) is a former professional American football player who played offensive guard for five seasons for the New York Jets.

David Rodger Hultgren (born April 30, 1951) is a former politician and judge in Illinois.

Ralph Greenleaf (November 3, 1899 in Monmouth, Illinois – March 15, 1950 in Philadelphia, Pennsylvania) was an American professional pool and carom billiards player. He was a twenty-time World Pocket Billiards Champion, who dominated the sport during his heyday.

James Montgomery Rice (March 8, 1842 - April 11, 1912) was an American soldier, lawyer, and public servant who contributed to the establishment of the United States National Guard.

Robert Clayton Dunbar (May 6, 1878 – June 22, 1973) was an American football player and coach. He served as the head football coach at Monmouth College in Monmouth, Illinois, where he was also a player and a student. Upon graduation, he attended Cornell University in Ithaca, New York.