Akasha

"The secretive Phayder Corporation developed the Necris treatment process to produce an elite group of "undead" assassins. The Necris process itself has no spiritual component, but those who have undergone the treatment have built up a religion based on this transformation. Over time, the Necris religion has become an important part of the Corporation's driving principles. Akasha is a Necris High Inquisitor, a ruthless leader who has ordered countless massacres."

- UT3 character description

Akasha is the leader of the Necris representation in UT3 and is hence the main antagonist in the Single Player campaign. The story explains she handles non-military ops such as the attack on Izanagi and Twin Souls.

Also from intial dialogue from Reaper as he hunted Akasha down she is in command of several crews: the Blackheart Assassins, Dark Phalanx Blades (curiously the Dark Phalanx was a team from Unreal Tournament, speculation: Necris conversion?) and the Black Legion themselves.