The Maiden's Blood Sisterhood is a compact of hunters that first appear in the book Night Stalkers. A secret society for college women similar to the Skull and Bones, they also happen to be hunters of vampires.
The Sisterhood has its origins, most appropriately, in the Seven Sisters of the Ivy League. In 1957, a Wellesley professor, Agatha Brewer, learned several of her students were being preyed upon by a vampire. Only after gathering select faculty and students were they able to make a stand and rid themselves of the bloodsucker for good. Realizing that this was not the end of the troubles with vampires, the group, with substantial financial backing from generous student and alumni, created an established sorority dedicated to keeping their campuses safe from the creatures of darkness.
Spread across several hundred college campuses, the Sisterhood is a loosely-organized network of secret societies, each dedicated to protecting their campus and the men and women in it from the creatures of darkness. By day, the groups are any ordinary sorority, helping out the community, but by night, they actively hunt down any threats to the college and local populations.
Started on a single campus, the Sisterhood continues to grow and spread. While the focus remains on youth and universities, there are members who have successfully survived and graduated, and have achieved recognition and positions of power in several fields, and are gaining footholds of influence in places that can help them further their cause.
While the group focuses on vampires and does not have issues with taking out other creatures of darkness, they do maintain an odd sort of respect for witches after a "witch hunt" resulted in the death of an innocent student. There are several rumors that many members, including a few high-ranking ones, are witches themselves.
The three major chapters of the Sisterhood are directly responsible for the daily operations of the group. The Pleiades are the national representatives and mediators of the group, the Amazons are the front-line fighters against the supernatural, and the Graces provide the support for the Sisterhood's more charitable works.
Hunter: The Vigil Organizations
Ahl al-Jabal · Ama-San · Ashwood Abbey · Azusa-Miko · The Bear Lodge · Barrett Commission · Bijin · Division Six · Habibti Ma · The Hunt Club · Illuminated Brotherhood · Keepers of the Source · Keepers of the Weave · Les Voyageurs · The Long Night · Loyalists of Thule · Maiden's Blood Sisterhood · Network Zero · Night Watch · Null Mysteriis · The Promethean Brotherhood · Protectors of the Light · The Reckoning · The Scarlet Watch · Talbot Group · The Union · Utopia Now · Yuri's Group
Aegis Kai Doru · Ascending Ones · The Cainite Heresy · Cheiron Group · The Faithful of Shulpae · Hototogisu · Knights of Saint Adrian · The Knights of Saint George · Les Mystères · Lucifuge · Malleus Maleficarum · The Merrick Institute · Otodo · Task Force: VALKYRIE · Vanguard Serial Crimes Unit