Lampreys

The Lampreys are a Alien race from Doctor Who. They exist outside of reality itself and are capable of being in multiple locations while feeding off chronon energy - the temporal energy generated by living beings as they exist. The Lampreys literally devour Time, liking nothing more than to find and completely extinguish an entire multiverse of realities just to feed. However, in order to actually enter a reality, they need to find a focus, unique mental waves of a time-sensitive individual, in order to home in on them and break through into their universe. See also

Lampreys