Vampire King

Vampire King is a terrorist orgainzation that has been active for nearly three decades. It is composed of vampires displeased with Yuki's rule changing their traditions, while also having humans who also wish for vampires to return to the shadows. They are opposed by the Hunter's Organization, the Night Class of Kaname's generation and the vigilante group lead by Maria Kurenai.

Trivia

 * It seems the vampires operate under the misguided belief of what Kaname's desires are, as the vampire who attempted to kill Ren said that the organization were the only ones who truly knew his will.