The Director

The Director (Sigourney Weaver) is the director of The Facility that is responsible for the keeping of The Ancient Ones and the main human/secondary antagonist of The Cabin in the Woods.

At the end of the film, she is heard over the intercom, telling Dana and Marty that they were never supposed to go down into the facility. When they get to the sacrificial room, she meets them and tells them that the entire thing was a ritual in order to stop the rise of the Ancient Ones and the end of the world. She tries to convince Dana to kill Marty; however, the werewolf attacks Dana and Marty attacks the Director. In the ensuing struggle, she fails to notice Patience Buckner, who kills her with an axe to the back of the head. Marty pushes the Director's body and Patience into the pit with the Ancient One.

Trivia

 * In a recent Q&A by Drew Goddard, he reveals that there are many facilites all over the world similar to the one featured in the film. This implies that perhaps the Director in the film is the Director of the North American Facility, and that there is a director assigned per facility globally.
 * Given the meta-fictional nature of everything else in the film, her title of "The Director" may imply how she is not unlike the director of a horror film with the Ancient Ones as the horror fans and audience.
 * Sigourney Weaver is well known for her role in the Alien series. She was previously in the Joss Whedon written Alien: Resurrection.