The Weeping Angels are an old and powerful race of quantum-locked creatures that resemble stone statues. They are very predatory and seek to create time paradoxes by sending someone back in time to a point before their birth and feeding off of the potential energy of the years the victim could have lived in the present. The Weeping Angels present themselves as stone statues due to their quantum-lock, meaning that whilst there is somebody watching them, they cannot move or act, they are “locked” in that form, unable to hurt anyone. However, as soon as the victim blinks or looks away, the Angel attacks and sends the person back in time. The Doctor faced the Weeping Angels multiple times, even losing companions Amy Pond and Rory Williams to the Angels.