The Kid’s official birth name was William Henry McCarty Jr. His birthplace is not certain. Some say New York City. In 1873 his mother, Catherine McCarty, married William Antrim and the family settled in Silver City, New Mexico. To avoid confusion with two Williams in the family she began calling the youngster by his middle name, Henry and the boy took his stepfather’s last name, becoming Henry Antrim. The family settled in Silver City, New Mexico in early April 1873. Catherine died on September 16th, 1874, of tuberculosis.
Henry Antrim began using William H. Bonney as an alias after he shot and killed Frank “Windy” Cahill during a fight in Arizona. Afterwards, he escaped and returned to New Mexico. The reason why he chose Bonney is unknown, but some speculate he chose the name because that was his biological father’s name before his mother married a man named McCarty.
Although the reason for the name “Bonney” is unknown, some speculate that this was his biological father’s name before his mother married a man named McCarty, who may or may not have been his biological father (not much is known of his biological father). McCarty may also have been his mother’s maiden name.
During the Lincoln County War his associates began calling him “The Kid” because of his youthfulness and slender build. In 1880, newspaper reporters and dime novelists who often embellished his deeds and his legend grew. So did the nickname that most people know him today, “Billy the Kid.”