Legendary gunfighter and lawman James Butler (Wild Bill) Hickok had a brother, nicknamed Tame Bill.
His brother's name was Lorenzo Butler Hickok. The origin of the nickname "Wild Bill" was unclear. One popular story told of how Hickok saw a man about to be beaten by a group of thugs and intervened. He drew his revolvers and threatened to shoot the first man to move. As nobody wanted to be shot, the crowd disperesed. (Source)
In 1876, Hickok was killed while playing poker in Deadwood, Dakota Territory. He was holding a pair of aces and a pair of eights, a hand that got to be called the "Dead Man's Hand."