Ultraman Jack (ウルトラマンジャック Urutoraman Jakku) is the villainous older brother of Father of Ultra, who was envious that his brother was picked over him for the title of the Inter Galactic Defense Force's Supreme Commander (大隊長 Dai Taichō). In retaliation, he started his own "New Inter Galactic Defense Force" and made himself dictator, until he was defeated by his former comrades. He only appeared in the 1979 Tetsuji Kataoka manga Ultra Brothers Story.
Ultra Brothers Story
Jack was the older brother of Father of Ultra, who was chosen to be the Great Commander of the Inter Galactic Defense Force by Ultraman King. Jealous of his younger sibling's accomplishment, Jack formed the New Inter Galactic Defense Force and declared himself to be Great Commander, though his organization quickly became a dictatorship. The New Inter Galactic Defense Force set out to crush anything Jack considered to be evil, which also consisted of anyone that Jack felt had wronged him. However, his insurrection was eventually crushed and Jack was killed by Ultraseven.
- While his name was used for "New Ultraman" years after his debut, there is no relation between the two.
- The concept of a friend/close relation to Father of Ultra turning evil would later be used for Ultraman Belial.