Lieutenant Commander Catherine-B320, commonly known as Kat, was a SPARTAN-III commando of the UNSC Naval Special Warfare Command, attached to Special Warfare Group Three. Catherine was described as an inspired tactician and an exemplary combatant, but also a brilliant cryptanalyst and a hacker; allegedly, there has not been a system yet that she had been unable to crack. According to Colonel Urban Holland, she had a habit of occasionally investigating classified Intel more than her superiors would have liked her to. Her ability to acquire and digest information has been described as "supernatural"; more than once, she had been able to read a situation, working with information many others would find overly limited. She fought as a part of Noble Team under the call sign Noble Two during the First War. She was part of the Chaos War.