This article is about the Didact encountered in Halo 4. For the Didact responsible for activating the Halo Array, see Iso-Didact.
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“The peaceful one is at war without and within.”
Mantle of Responsibility, Fifth Permutation of the Didact's Number

Shadow-of-Sundered-Star,[3] more commonly known as the Ur-Didact (Ur- meaning original), was a Forerunner Promethean who held an extremely high status in the Forerunner society as supreme commander of the entire Forerunner military.[4] 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,[5] 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.[6] The Ur-Didact was eventually exiled on Requiem, not to be awakened until 2557,[7][8] while the Bornstellar-Didact served during the final days of the Flood conflict, and was also the individual responsible for activating the Halo Array.[4][9]


“We are Forerunners, guardians of all that exists!”
— Ur-Didact

Warrior-Servant careerEdit

VLCpic-HALO4 Terminal Didact1

The Didact's armor during the beginning of the Human-Forerunner war

The Didact was a Promethean, a member of an extremely powerful class of Warrior-Servant. He gained his name while teaching at the College of Strategic Defense of the Mantle. On Charum Hakkor, he met a Lifeworker named the Librarian and married her. They had several children, who followed their father's footsteps and became Warrior-Servants. During the Human-Forerunner war, the Didact led the Forerunner military against the humans. Though all of his children were killed, the Forerunners were victorious. After the Charum Hakkor campaign, he and a group of Prometheans, including the Confirmer, discovered a stasis capsule on Charum Hakkor which contained the Timeless One, the last of the Precursors.

Following the end of the war and the first discovery of the Flood, he advocated a policy of vigilance and research in the event of a Flood resurgence. He also proposed the construction of Shield Worlds across the galaxy, in order to monitor the galaxy for Flood outbreaks and provide military support should they occur. However, a faction of Builders led by Faber proposed the construction of a series of superweapons to deal with the Flood instead, and they were successful in convincing the Forerunner Council to sanction their plans. Having lost the political battle, the Didact was stripped of his power and forced into exile.

Discovery on Erde-TyreneEdit

In his exile, the Didact entered a state of meditation inside of a Cryptum, which was placed by the Librarian in Djamonkin Crater on Earth. Over one thousand years later, he was discovered and revived by a young Forerunner Manipular, Bornstellar-Makes-Eternal-Lasting, who had come to Earth in search of Precursor relics.

During his subsequent travels with Bornstellar, the Didact performed a brevet mutation on the young Bornstellar to allow him access to the Domain. With the mutation, the Didact transferred all of his memories and knowledge to Bornstellar. This made Bornstellar essentially a copy of the original Didact. The original Didact, or the Ur-Didact, was later left in a Flood-infested system by the Master Builder. After surviving the 032 Mendicant Bias' assault on Maethrillian, Bornstellar Didact would reunite with his wife, the Librarian on Installation 00 and resume his duties as supreme commander of Forerunner military due to the present threat of the Flood.[10]

Forerunner-Flood warEdit


Ur-Didact before he begun experimenting on himself.

At some point during the Forerunner-Flood war, the Ur-Didact began to experiment on himself in an attempt to gain immunity to Flood infection. When his efforts ended in failure, a subordinate suggested the Composer as a solution. Since the Composer did not work on his new form, his Prometheans all volunteered to undergo the process, becoming the first Promethean Knights.[11]

“Humans, your kind brought the Flood to our shores. Now you will aid in ending its threat.”
— Ur-Didact
“I have led you, my Prometheans, for thousands of years, and I shall continue to lead you. Rise. Rise and protect the Forerunners. Rise, and protect the galaxy!”
— Ur-Didact to his newly formed army of Promethean Knights, on their task to remove the Flood threat from the galaxy

Despite this new army of soldiers no longer susceptible to Flood infection, their numbers were too few to prevent the parasite from continuing to spread. Seeking to both increase the size of his army and exact a measure of revenge for their actions during the previous conflict, the Ur-Didact would turn the Composer upon humanity; planning to eventually have the entire species composed and turned into new Prometheans.

After seeing the results of his "conscripting" one human village on Omega Halo, the Librarian would remove the Composer from the Ur-Didact's custody and seal both him and his Knights away inside Requiem, putting an end to the Ur-Didact's plans and sentencing the galaxy to the activation of the Halo Array.


DIdact with armor

The Ur-Didact shortly after awakening in 2557.

The Ur-Didact[12] was sealed in a Cryptum that required a Reclaimer to activate and release him. In 2557, the Ur-Didact tricked John-117 into releasing him by manipulating transmission signals from UNSC Infinity, leading him to the center of Requiem under the pretense that it was a transmission network. The Didact, with Jul 'Mdama's Covenant now at his command, launched an assault on the grounded Infinity, but UNSC forces, aided by John-117, were able to push back the assault and even drive the Didact's vessel away.

The Didact began a search for the Composer, a device that turns living beings into digital forms, at Ivanoff Research Station orbiting Halo Installation 03. He was followed by John-117. After arriving at his destination and fighting the UNSC forces there, the Didact obtained the Composer and fired it at Ivanoff Station, instantly killing all UNSC personnel aboard. However, John-117 survived due to the Librarian's genetic manipulation which made him immune to the effects of the Composer.

The Didact then departed for Earth to create a new Promethean army by transforming the entire human race into Prometheans using the composer. Again, John-117 followed him. Upon arriving at Earth, the Didact was immediately attacked by a UNSC fleet led by Infinity. Infinity was able to make a hole in the Forerunner vessel's hull which allowed John-117 to board it.


Before John-117 made it to the Didact, the Didact fired the Composer at Earth, composing all of the inhabitants of New Phoenix. John engaged the Didact, but the Didact constrained John using telekinesis. Cortana, contained in the Mantle's Approaches network, manifested copies of herself into nearby hardlight particles and used the particles to restrain the Didact long enough for John to plant a Pulse Grenade on his chest. It detonated, wounding him and causing him to fall off the light bridge and into the slipspace event below. John then destroyed the Composer and the Didact's vessel with a Havok nuclear bomb.

Composer's ForgeEdit

Ur-Didact alive

The Ur-Didact still alive after falling through the Slipspace fissure.

Among the high-ranking officials in the UNSC, it was assumed the Didact had died when falling into the slipspace event; even though no body was ever found. In order to keep the human population at ease, they decided not to disclose to them a live Forerunner had been encountered. The attack on New Phoenix was to be blamed on Jul 'Mdama's Covenant.

Unbeknownst to the UNSC, on July 25, 2557, the Didact ended up on Installation 03, where he was found by Team Black. Regaining consciousness, the Didact attacked the Spartans on sight, killing them and the science team nearby with his bare hands. He then came into contact with 859 Static Carillon, the keeper of the Composers and inquired how he came to Halo. When the Monitor explained that he came to the Halo in response to the service portal being opened and the ring's Monitor being unresponsive. Realizing that the portal lead to the Composer's Forge, where he could acquire additional Composers, the Didact asked to be brought there.

The next day, Blue Team and the Master Chief were sent to search for Team Black. After finding their dead bodies, Blue Team investigates the Forerunner structure which used to hold the Composer before it was moved. While investigating the structure, they stumbled upon the Composer's Abyss, the location of all the subjects which were 'digitized' by the Composer. As soon as they entered, Static Carillon alerted the Didact to the Spartans' presence.[13]

The Didact appeared before the Spartans, holding the Activation Index in his hand. The Spartans open fire but the Forerunner repels them before summoning Prometheans to attack them. As the Spartans began to defend themselves, Static flew down to protest the Didact's blatant manufacturing of Prometheans in direct violation of their compact. The Didact assured the Monitors that his Prometheans would be moved to Requiem soon. However, the Monitor was more concerned that he used unwilling humans to make them. The Forerunner proceeded to grab the Monitor and order him to fulfill his end of their bargain, as the Halo appears in the sky over the Forge. The Didact then returned to the ring to affect repairs and replace the Composer, planning on firing it near Earth to wipe out humanity. The Spartans managed to follow him back, but the Didact merely swept Blue Team aside. The Master Chief attempted to stab the Didact in the right eye, but he showed no sign of pain as he grabbed his enemy by the helmet and began to squeeze.[14]

Blue Team attacked the Didact, but he had attuned his armor to their weapons, rendering them useless. As he was about to finish them off, the Monitor attacked him and then transported him into Installation 03's control room. When he regained consciousness, the Master Chief entered and put the Index into the control panel. The Didact asked if the Master Chief intended to fire the ring just to kill him. He said he had thought of it, but didn't want to also kill all life in 25,000 light years around the ring. Instead, he had 859 Static Carillon deactivate Installation 03's fail-safes and detach a section of the Halo, which fell to the planet below, impacting the Composer's Forge and destroying the five Composers stored there. John-117 was teleported to safety by Static Carillon, while the Didact was disintegrated.[15]



  • "Didact" is derived from the Greek word "didactic," which means to instruct others, especially with regard to morals.
  • Didact is the first Forerunner whose face is shown in the series.
  • In Halo 4, the Ur-Didact was voiced by Keith Szarabajka, who is also known for his performances as Dr. Kyne in Dead Space and Harbinger in Mass Effect 2 and Mass Effect 3.
  • A Didact figure is included in the McFarlane Toys Halo 4 Series 2 line.



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