Adepta Sororitas

The Adepta Sororitas, also known as the Sisters of Battle, are the female warriors belonging to the religious arm of the Imperial government, known as the Adeptus Ministorum, or Ecclesiarchy. They have recently become tied to a part of the Imperial Inquisition which is tasked to hunt down and destroy heretics and unsanctioned psychics (commonly known as "rogue psykers"), which obviously has strong ties to the Ecclesiarchy.

Interestingly, they were originally just the militant arm of the Ecclesiarchy. During the reign of a despot who managed to use the Ecclesiarchy to subvert the Imperial government, the Sisters of Battle, as well as the male version known as the Frateris Templar, became the personal armies of the despot. Eventually the Sisters were convinced that he was in fact a traitor, and the leader of the Sisters at the time executed him. After this episode, the Ecclesiarchy was forbidden to have any "men" under arms in their service, so the Frateris Templar were disbanded and the Sisters became their sole military force. Obeying the letter of the law, but not the intention.

Though not genetically enhanced like the Space Marines, they do wear similar heavy armor and have the same general unit set-up, although they tend to prefer heat and flame based weapons, for the 'purifying' effect of fire. They also gain powerful faith-based powers to help them combat their foes.