This unnamed woman served as the vessel of the Apocalypse World version of the Archangel Michael.
History[]
At a unknown point after he left Dean's body, Michael took this woman as his vessel in the principal universe.
Michael used this woman for his operations to attack Kansas City. It is also used when Michael comes to destroy the exorcization egg in front of Sam Winchester's eyes. Later, Dean, armed with Kaia's spear, comes to the desk where Michael is sitting. Michael then leaves this woman's body and takes over Dean as his primary vessel.
This woman's current status is completely unknown to us but it is likely that she is dead.