Task: Question Answering
Input (English): Passage: John Chisum, a virtuous, patriarchal land baron, locks horns with greedy Lawrence Murphy, who will stop at nothing to get control of the trade and even the law in Lincoln County, New Mexico Territory.
Chisum is an aging rancher with an eventful past and a paternalistic nature towards his companions and community. Murphy, a malevolent land developer, plans to take control of the county for his own personal gain.
The story begins with Murphy's men tipping off Mexican rustlers who plan to steal Chisum's horses. Chisum and his sidekick James Pepper stop the bandits with help from a newcomer to the area, William H. Bonney, also known as "Billy the Kid". A notorious killer, Billy has been given a chance to reform by Chisum's philanthropic British neighbor, rancher Henry Tunstall. Billy also falls for Chisum's newly arrived niece, Sallie.
Murphy is buying up all the stores in town and using his monopoly to push up the prices. He appoints his own county sheriff and deputies. He also brings in a lawyer, Alexander McSween, whose principles lead him to switch sides and seek work with Chisum and Tunstall. The two ranchers set up their own bank and general store in town under McSween's control.
Chisum's land and cattle remain targets. Murphy's men attempt to steal Chisum's cattle before he can sell them to the United States Army. Chisum's ranch hands are warned by Pat Garrett, a passing buffalo hunter. Garrett agrees to help Chisum and soon befriends Bonney. Together they foil an attack by Murphy's men on the wagons bringing in provisions for the new store. 
Question: What is the nickname of the person who helps Chisum and his sidekick stop the bandits?
Output (English): Billy the Kid.