John "Jack" McClane Jr. is the youngest child of John McClane and Holly Gennero and the older brother of Lucy McClane. As a child he was played by Noah Land and as an adult he was played by Jai Courtney. In A Good Day to Die Hard it is revealed that McClane is an undercover C.I.A. agent.
Die Hard[]
Jack appears briefly as a young child in the opening of the movie. He and Lucy were seen playing in the kitchen. After this he would not be seen again.
A Good Day to Die Hard[]
John McClane Jr. is introduced as John McClane's estranged son. He is at odds with his father but cut from the same cloth. While at a Moscow nightclub he killed a man named Anton, who was revealed to be an associate of corrupt high-ranking Russian official Viktor Chagarin. At a Russian prison, Jack makes a deal for a lighter sentence in exchange for his testimony on Yuri Komarov so he can get close to Komarov and save his life. It is later revealed that Jack is a C.I.A. deepcover agent on a three year mission in Russia to get evidence against Chagarin while getting government informant, Chagarin's ex-partner Yuri Komarov, to help to get evidence against Chagarin. Yuri told McClane that there was an incriminating file on Chagarin inside a vault. However, when Yuri, John McClane Sr. and Jr. arrive they learn that the information in the file was not evidence against Chagarin but instead a file on a secret passage to to a vault containing a large amount of weapons-grade uranium. One of Yuri's ment then kills Chagarin. John McClane Jr. then chases after Yuri and have a shoot out on the roof of a building. During the fight Yuri falls oof the side of the roof and and dies when he falls into the blades of a helicopter that John McClane Sr. is flying. John and Jack then return to America where they are greted by Lucy.