Ancient One

The Ancient One appeared in the 2012 movie called The Cabin in the Woods. Its a giant shadow demon that lived right under the facility that houses these monsters and it will rise and cause destruction on humanity, however in order to prevent this from happening the facility has to do is make a sacrifice, by using the victims that are staying at the cabin for a night and a monster that's been summon by using one of the required objects to summon a specific monster.