Serina

Serina is an Artificial Intelligence (AI) construct that is assigned to the UNSC Spirit of Fire, a modified Phoenix-class Colony Ship. She is set to be one of the main characters in the upcoming Halo Wars, helping the player as they play the game.

Overview
Little is known about Serina at this point in time, other than the fact that she acts as a military advisory AI, which may or may not be her only function. Her Avatar is currently unknown as no details on it have yet been released. However, it is likely that she will be similar to Cortana. Although it is unknown if she is a smart or dumb AI.

She was also mentioned in a UK published "Game Master" magazine.

Quotes
"What the heck is that?!" (When seeing a Covenant Scarab coming out from a hole)

"Well, this is new... and scary." (upon seeing a Covenant Scarab)

"The MAC is online and primed. Payback time!"

Trivia

 * Serina's role as an artificial intelligence guiding the player in-game can be considered analogous to the EVA of Command and Conquer and/or the Adjutant of StarCraft.