Francis Augustus Hamer ('he?m?) (March 17, 1884 – July 10, 1955) was the Texas Ranger who led the 1934 posse that tracked down and killed criminals Bonnie Parker and Clyde Barrow.
Renowned for his toughness, marksmanship, and investigative skill, he acquired status in the Southwest as the archetypal Texas Ranger.
Hamer also led the fight in Texas against the Ku Klux Klan starting in 1922 as senior captain of the Texas Rangers, and he is believed to have saved at least fifteen people from lynch mobs.
He was inducted into the Texas Ranger Hall of Fame.
His professional record and reputation are not without controversy, particularly with regard to his willingness to use deadly force even in an increasingly modernized society.
Overall, because of his sustained excellence and numerous exploits in a career that spanned more than forty years, Hamer has been described by biographer John Boessenecker, historian Robert Utley, and other experts on criminal justice in the United States as "one of the greatest American lawmen of the twentieth century".