[bcsco]

Most historians today go with the theory that the Kid’s name was really Henry McCarty, born in New York City. “Bonney” was an alias. His mother later married a William Antrim and he also was called “Kid Antrim”. He only became known as “Billy the Kid” after his exploits in New Mexico became widely known. I think that name came from dime novelists...

[JoeProBono]

Henry McCarty was born in Manhattan on November 20, 1859. Henry and his older brother Joe, born in 1854, were both illegitimate. Their father was Edward McCarty, a married man with two daughters and a son in Brooklyn. Although Henry had a short life, his brother Joe lived to be 76 years old. Henry grew up to use the names Henry Atrim, William Bonney, and Billy the Kid. According to the New York police "Michael" Henry McCarty was a delinquent as a small boy.