Brakari

Brakari were a type of spacedwelling animals.

Biology
Brakari were globular, jellyfish-like creature. They were normally bright white with blue specks, but became grey when sick. They were capable of levitating, but when hungry were forced to slither on the ground. Though they weren't sentient, they still took care of their offspring.

The Brakari were capable of travelling through the vacuum of space. In order to survive the trip, they were able to store energy, draining heat from objects to do so. A full-grown adult could drain all the energy from a Human in seconds. (WC: Snowfall)

History
At some point in the 21st century, a sick Brakari gave birth, leading to an even sicker offspring. They came to Earth and tried to find a source of energy, attempting to drain it from a theatre. When the Doctor, Louie Rollins, Millie Peterson, their Aunt Rachael and Big Jack came to the theatre, they also tried to feed on them, but were driven off by the Doctor's sonic screwdriver. When the Doctor learned the truth of the matter, he was able to use equipment from TARDIS to restore the Brakari to full health. (WC: Snowfall)