Shadow-of-Sundered-Star, more commonly known as the Ur-Didact (Ur- meaning original), is a Forerunner Promethean who held an extremely high status in the Forerunner society as supreme commander of the entire Forerunner military. He wholeheartedly believed in the Mantle of Responsibility the Forerunners held to protect life, and initially opposed the Halo Array as a sin beyond measure. He was also the lover and husband of The Librarian. He serves as the primary antagonist in Halo 4.
Originally thought to have been physically killed by the former Master Builder Faber, the Didact effectively existed as two individuals during the final days of the Forerunner-Flood war; his original self, as well as his implanted consciousness within a young Forerunner known as Bornstellar Makes Eternal Lasting. To differentiate these two incarnations, the original Didact was referred to as the Ur-Didact, while his other incarnation was known as the Bornstellar-Didact or Iso-Didact. The Ur-Didact was eventually exiled on Requiem, not to be awakened until 2557, while the Bornstellar-Didact served during the final days of the Flood conflict, and was also the individual responsible for activating the Halo Array.
- Didact blames human for the Flood and seeks to wipe out human kind.
- Didact was once a good friend of Darkblade until went bad.
- Didact will become Twilight's enemy in Twilight's Adventures of Halo 4, and after his body was found from the deep space by Anubis, he'll join his army of darkness called The Heylin Empire and revenge on Twilight and the Rainbooms, especially Master Chief and become part of her and her team's dangerous and powerful foes.