Ilsa Zane was one of the original SPARTAN-IV's and is the leader of an Insurrectionist group consisting of at least 7 other people who acquired information about UNSC Infinity and decided to steal it.
Ilsa Zane was one of the original SPARTAN-IVs that were intended to not need Mjolnir Armor, but achieve the same feats as a person wearing the armor. The augmentations were considered too costly for the candidate, killing or crippling the other nine inductees, while Zane became very unstable. She was then transferred out of the program and into the Office of Naval Intelligence, only to defect to the Insurrectionist cause.
Eventually leading an Insurrectionist cell of the New Colonial Alliance in 2553, Ilsa discovered the existence of the Infinity. As one of her colleagues assumed that the massive warship would be used to police the colonies, Ilsa proposed that they capture the ship.
Ilsa and her crew disguised themselves as construction workers and slipped into the Infinity. As Infinity only housed a few hundred crewmen, Ilsa captured Captain Del Rio and deactivated the AI Aine when she recognized her. Once in control of the bridge, she addressed the entire crew, threatening to vent three miles of the ship into space if anyone tried to interfere. After hearing this message, the SPARTAN-IV Sarah Palmer went to the armory with Thomas Lasky and put on the Scout variant of the MJOLNIR GEN2 armor.
Once Ilsa Zane found out about the SPARTANs, she depressurized the Spartan Deck, believing that would be enough to stop them. She then sent down a strike team to eliminate them more thoroughly, when she found out her previous action was unsuccessful. As her strike team battled three SPARTANs, Jun and Lasky, Palmer and Davis were outside of the ship climbing in through the bridges viewports. They then broke through the Bridge's viewports and ambushed Ilsa and four other Insurrectionists. Ilsa engaged Palmer while Davis engaged the four Insurrectionists. Davis neutralized the four soldiers, while Ilsa was winning the brawl with Palmer, wrapping her hands around her opponents' throat, until Captain Del Rio reactivated Aine, who had depressurized the bridge. Palmer then knocked Ilsa out into the void of space, only to have Ilsa be picked up by a Prowler crewed by insurrectionist loyalists. Upon being resuscitated, she was startled upon recognizing someone familiar. 
By 2558, Ilsa Zane was in command of a large cell of New Colonial Alliance rebels investigating the events on Conrad's Point. She commanded them with an iron fist, killing those that she felt didn't belong. She was last seen firing at a pelican being used by Maya Sankar to escape the rebel base after a UNSC airstrike.
- Her name is misspelled as 'Isla' when she talks to the crew of Infinity via the intercom.
- Halo: Initiation (First appearance)
- Hunt The Truth