Silver Timeline

Catherine Halsey/Silver

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This article contains information from the Silver Timeline universe, and is not a part of the established Halo canon. To see information about this article's counterpart in the canon Halo universe, see here
Catherine Halsey
Catherine Halsey vibin
Biographical information


Miranda Keyes

Personal details





Political and military information


United Nations Space Command


Civilian scientist


Doctor Catherine Elizabeth Halsey is a civilian scientist for the UNSC. She is the creator of the Spartan super soldiers, particularly the SPARTAN-II's.[1]


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Early life and career[edit]

Not much is known of Halsey's early life in the Silver timeline, but she had worked on the planet Onyx in her early days as a UNSC scientist.

Finding John and the other SPARTAN candidates[edit]

Creating Cortana and dealing with a rogue Master Chief[edit]

Return to Eridanus II[edit]

At conflict with ONI, Chief and everyone[edit]

Desperate power grab attempt and escape[edit]

In ONI custody[edit]

Reunion with the deserter and the Fall of Reach[edit]

Coming to terms with John[edit]

Reunion with Miranda on Onyx and cracking Forerunner secrets[edit]

Infection by the Flood[edit]

Personality and traits[edit]

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A brilliant but overly ambitious scientist, Catherine Halsey is devoted to the advancement of humanity, but will often use unethical means to achieve it, such as using and killing a live clone of herself to create Cortana, kidnapping and enlisting children against their will into the SPARTAN-II program before wiping their memories and subjecting them to horrific augmentations, and attempting to replace the human consciousness of the SPARTAN-II's with AI to make them "more controllable", as she attempted to do with John-117 and Cortana. This eventually put her at odds with ONI, the UNSC, and even with her SPARTANs when they discovered the truth of their upbringing and her ultimate intentions.

Production notes[edit]

Catherine Halsey in Halo: The Television Series is portrayed by actress Natascha McElhone.[1] McElhone was originally cast to play both Halsey and Cortana, much like Jen Taylor did for Halo 4, Halo 5: Guardians, and Halo Infinite. However, due to scheduling difficulties caused by the COVID-19 pandemic, McElhone was unable to complete her work as Cortana, so Jen Taylor was brought onboard the project to reprise her role from the games.[2]


List of appearances[edit]