Cortana is a fictional artificially intelligent character in the Halo video game series. Voiced by Jen Taylor, she appears in Halo: Combat Evolved and its sequels, Halo 2, Halo 3, Halo 4, Halo 5: Guardians and Halo Infinite. She also briefly appears in the prequel Halo: Reach, as well as in several of the franchise's novels, comics, and merchandise. During gameplay, Cortana provides backstory and tactical information to the player, who often assumes the role of Master Chief Petty Officer John-117. In the story, she is instrumental in preventing the activation of the Halo installations, which would have destroyed all sentient life in the galaxy. Cortana's original design was based on the Egyptian queen Nefertiti; the character's holographic representation always takes the form of a woman. Game developer Bungie first introduced Cortana—and Halo—through the Cortana Letters, emails sent during Combat Evolveds production in 1999. The relationship between Cortana and Master Chief has been highlighted by reviewers as one of the most important parts of the Halo games' story. Cortana has been recognized for her believability and character depth, as well as her sex appeal. The character was the inspiration for Microsoft's intelligent personal assistant of the same name. Description Cortana is an artificial intelligence found in the Halo franchise. In the video games, Cortana often serves as an advisor and assistant to the player character, hacking alien computer systems and decoding transmissions. She speaks most of the first game's dialogue, and serves as a talkative foil for the quieter Master Chief, as well as a way of relaying information and objectives to the player. According to her backstory, Cortana was derived from the cloned brain of Dr. Catherine Elizabeth Halsey, the creator of the SPARTAN-II supersoldier project; Halsey's synapses became the basis for Cortana's processors. Cortana and other AIs are subject to a seven-year lifespan, after which they begin to dissemble and think themselves to death in a process known as rampancy. As an artificial construct, Cortana has no physical form or being. Cortana speaks with a smooth female voice, and projects a holographic image of herself as a woman. Cortana is said to resemble Halsey, with a similar attitude "unchecked by military and social protocol". In Halo: The Fall of Reach, Cortana is described as slender, with close-cropped hair and a skin hue that varies from navy blue to lavender, depending on her mood. Numbers and symbols flash across