Hickok was born in Troy Grove, Illinois. He left his father's farm in 1855 to be a stagecoach driver on the Sante Fe and Oregon Trails. His gunfighting skills led to his nickname. In 1861, he became a town constable in Nebraska. He became well-known for single-handedly capturing the McCanles gang (through the use of a ruse).
After the American Civil War, Hickok became an army scout and a professional gambler. In 1867, his fame increased from an interview by Henry Stanley. In 1871, Hickok became marshal of Abilene, Texas. He toured with Buffalo Bill's Wild West show in 1872-1873, where he was romantically linked to Calamity Jane. He was fired from the show due to drunkenness.
In 1876, while playing poker in Deadwood, South Dakota, Hickok was shot dead by Jack McCall, who thought that Hickok shot McCall's brother in Kansas. At the time of his death, Hickok held a pair of Aces and a pair of eights, which has since been known as a dead man's hand.