Backstory, Cortana & Spartan Program


Here’s everything you need to know about Dr. Catherine Halsey, the controversial creator of Halo‘s Spartan program. Played by Natascha McElhone (The Truman ShowRoninSolarisDesignated Survivor), Dr. Halsey is an ambiguous figure in the world of Halo. To the Spartans, she’s almost like a mother figure – but in reality, they would be wiser not to trust her at all.

Dr. Halsey’s name probably won’t be familiar to fans who only played the first few Halo games, although she does appear in more recent installments. The character first appeared in official tie-in novels, and the Halo TV series is remarkably faithful to the source material. Even an unexpected relationship between Halsey and Miranda Keyes is actually lifted straight from the original canon, which may surprise many viewers. Paramount+’s Halo TV series clearly sees the ethically ambiguous Dr. Halsey as key to its world-building, and she feels to be more of an antagonist than an ally.


Related: Halo Show’s Silver Team vs The Games’ Blue Team: What’s The Difference?

All this means viewers will certainly be interested to learn more about Dr. Halsey’s backstory. Given the similarities between the Halo TV show’s so-called “Silver Timeline” and the original canon, it’s reasonable to assume most of the beats are the same. Here’s everything you need to know about Dr. Catherine Halsey.

Dr. Catherine Halsey Origin Explained

Halo Dr Halsey

Dr. Catherine Halsey was born on the colony world of Endymion in 2492. According to Eric Nylund’s novel Halo: The Fall of Reach, in the original Halo timeline, the young Catherine Halsey was “smarter than her parents, always reading, talking, learning, and eager to share her knowledge with anyone who would listen.” Halsey attended an elite academy on her homeworld, and impressed the Dean of Biological Science at Koletre-Browning University so much that he paid for her education for several years. By the time she was 15, Halsey was writing her second doctoral thesis, and in 2510, the 18-year-old was recruited by the Office of Naval Intelligence as a civilian adviser. So began a prestigious career in which Halsey became increasingly involved with ONI black ops experiments. The Halo TV series seems to be diving into the dark side of the UNSC and the ONI, with episode 1 introducing the shocking Article 72 twist as a prime example.

Dr. Halsey was always career-driven, although that didn’t mean she never took lovers. She had a relationship with Captain Jacob Keyes, and in 2525 she gave birth to their daughter, Miranda. The relationship with Keyes didn’t last, and while Dr. Halsey originally had custody of their daughter she sent Miranda to be with her father on Luna Colony in 2531. Halsey and Miranda seem to have had a sharp falling-out, with Miranda changing her surname to Keyes and pursuing a military career, which her mother felt was purely an attempt to earn her father’s approval.

Dr. Halsey & Spartan Program: Creation & Controversy

Halo Master Chief Dr Halsey

Dr. Halsey is best known for her Spartan program, genetically engineered supersoldiers created to oppose an Insurrectionist movement that threatened to tear the UNSC apart. Halsey obtained genetic samples from children across the galaxy and hand-picked her recruits; she had these children kidnapped, some of whom were as young as six years of age. Many were orphans, but those who had a family were replaced by flash clones designed to deteriorate and die over the next few months. These 70 children were then given intensive military training, essentially becoming child soldiers, much to the discomfort of other UNSC troops they sometimes trained against. The whole process – the kidnapping, the flash cloning, and the training of child soldiers – was entirely illegal and incredibly unethical.

Related: Halo Show: Why Master Chief’s Voice Actor Was Recast (But Cortana Wasn’t)

When the Spartans became teenagers, they were subjected to genetic engineering and received extensive cybernetic implants. Only around 30 of the children survived the process, while some 12 or so were injured too badly to fight afterward but retained extensive abilities that meant they were still of use to the UNSC. Dr. Halsey then began to send these teenagers on combat missions against the Insurrectionists, even sending John-117 – the Spartan who would become the Master Chief of Halo – to his home system of Eridanus. The final stage of Dr. Halsey’s Spartan program was barely ready before an alien Covenant invaded the galaxy, suddenly making this more important than ever before. She had her Spartans don powerful Mjolnir exo-armor, sophisticated battlesuits they alone could wear because of the experiments that had been conducted on them years ago.

How Dr. Halsey Created Cortana

Dr Halsey and Cortana Clone Pod in Halo Episode 1

The Spartans were only the beginning of Dr. Halsey’s unethical experiments, though. She resolved to create the ultimate generation of artificial intelligence, and, egotistical to the core, chose to model this AI on her own brain patterns. This led Dr. Halsey to create the AI Cortana, but, again, the process she used was completely illegal. The only way to create a duplicate brain pattern is through a process called Cognitive Impression Modelling, which destroys the donor brain. Dr. Halsey circumvented this by again using illegal flash cloning to create unstable duplicates of her own mind; flash clones actually retain memories, so Halsey was able to then subject the clones to a CIM process. Dr. Halsey attempted to create over 20 of these AIs, but only managed to fashion two, Cortana and another named Kalmiya. In the Halo games timeline, Dr. Halsey gave Cortana a free choice over which Spartan she should be bonded to. Like Halsey, Cortana was impressed by the Master Chief, particularly by his luck.

Dr. Halsey’s Role In The UNSC

Halo Reach Surface

Dr. Halsey works for the UNSC’s Office of Naval Intelligence, specializing in black ops projects the UNSC officially classifies as top secret. Her record of success means she’s given remarkable leeway when it comes to managing her projects, and she has enough pull with senior figures in the ONI to get her own way. For all that’s the case, though, Dr. Halsey’s unethical and illegal methods have often left her superiors deeply uncomfortable. Some choose to remain ignorant, allowing Halsey to do things however she sees fit, but others have been quite active in looking for an opportunity to bring her down. Halsey’s career was frequently threatened when details of the Spartan program leaked outside her closest circle of allies, but she shared the Master Chief’s own luck; on many occasions, admirals who planned to bring her down subsequently died in battles fought during the Human-Covenant War.

The Spartans tend to view Dr. Halsey as a mother figure, and they’ve been conditioned to show her absolute loyalty. They’re unwise to do so, of course, because although she advocates for the Spartans she’s well able to put emotional considerations behind her in the face of what she considers to be the greater good. Halo episode 1 sets up Dr. Halsey as another villain rather than an ally, meaning the relationship between Halsey and the Spartans may well come crashing down.

More: What Is The Object Master Chief Finds In The Halo TV Show?

Halo releases new episodes Thursdays on Paramount+.


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