Avatar

An Avatar is the physical representation of an Artificial Intelligence or AI, used as a way to better interact with Humans.

This is the avatar of the AI Cortana.

While not used by all AIs, every "smart" AI uses an avatar as do many "dumb" AIs. This physical representation is chosen by the AI upon their creation and can be whatever they desire it to be, although the duty which the A.I. is to perform, combined with the Human brain that was used to create it, (like Melissa) have a great deal to do with what avatar they chose to appear as.

Here is a list of known UNSC A.I.s and their avatars:

Araquiel: An elongated skull with long, demon-like horns, fire filled eyes and jagged teeth.

Beowulf: A man wearing a hooded cloak.

Cortana: Tall and slender with short-cut hair in Halo: Combat Evolved, then long hair in Halo 2 and Halo 3.

Deep Winter: An old man with a snowy cape, often accompanied by holographic ice and snow.

Déjà: The appearance of a Greek goddess: barefoot, wrapped in the toga, motes of light dancing about her luminous white hair and holds a clay tablet in her left hand.

Endless Summer: A tall, red Cherokee Indian chief, bare-chested, wearing buckskins, and with a feathered spear in hand.

Jerrod: A tiny spark of light with a formal butler voice.

Lysithea: A sweet feminine voice with a laugh that sounds like "fine bone china clinking together."

Mack: He used the avatar of an American Cowboy from the 20th century.

Melissa: Tall and slender with long hair, Marathon symbol on her left shoulder. Yellow or black or brown, depending on the image.

Sif: Wears an ankle-length, sleeveless gown of "interwoven sunset hues" and has long, golden hair, which falls "in waves to the middle of her back".

For more detailed information of known AIs that use avatars, please see the list of the Artificial Intelligence serving the United Nations Space Command.