Explanation:
In the 1990 film adaptation, Jack is portrayed by Chris Furrh. He is sixteen, two years older than Ralph, and has blond hair. Like all the other boys in this version of the story, Jack is American and attends an unnamed American military boarding school. He wears the rank insignia for cadet first lieutenant, making him the third-ranked cadet on the island, after Cadet Lieutenant Colonel Ralph and Cadet Captain Roger.
Jack in this version speaks faster than his British counterpart in the 1963 film does, and more often. He swears violently, more than anyone else in the film. He is vain, arrogant, and immature, but as he becomes leader of the Hunters and then ousts Ralph as the Chief, he quickly adopts a brutal and authoritarian style of leadership. In this version of the story, several boys leave with Jack immediately when he declares he will form his own camp. Jack relies on Roger throughout the film as a right-hand-man and enforcer.
Jack is visibly shocked when Roger kills Piggy, but does nothing about it. Instead, he drives Ralph away and soon sets most of the island on fire in an effort to force Ralph out of hiding. When U.S. Marines land just as the boys are about to kill Ralph, Jack, like the others, is completely surprised and unsure of what to do.
Jack's last name is never said in the 1990 film, or is his cadet rank actually referred to. He quickly dispenses with his uniform and any formalities of military rank, in any case, and all the boys simply refer to and address him as "Jack", or as "Chief" once he has overthrown Ralph and taken charge as the new leader.