Cerebravore

Cerebravores were intelligent predatory psi-forms created from Pranavores by experiments performed by Fleshkind.

Biology
Cerebravores were originally created to be used for military purposes in the psychosphere of an alien planet. Being psi-forms they were not perceptible to most corporeal creatures. They fed on fear and dark emotions. Cerebravores preyed by first scaring a victim telepathically magnifying its worst fears. If the victim turned out to be susceptible, they could use it as a host and manifest themselves physically. By this stage, they could generate fear both inwardly to the host and outwardly manifesting the worst fears of potential future victims. Eventually, the host would die of exhaustion and the cerebravore would search for another.

When Gabby Gonzalez was looking at Cerebravores using headgear with a special ocular circuit for observing psi-forms, she described them as spidery reptile things.

Culture
Cerebravores developed an individualistic predatorial culture based on silence. They called their activities "the silent hunt" that happens under "the holy veil of quiet". They disdained species whose bodies consisted of substance, but attacked psi-forms and flesh-based creatures alike.

History
A species whom Cerebravores called Fleshikind tried to weaponise local Pranavores by separating them from their hive mind. Without it, Pranavores mutated and became Cerebravores, who attacked and consumed all of the Fleshkind. After laying waste to their own planet, Cerebravores managed to create an interdimensional gateway from their planet to Earth. On Earth, the first Cerebravores emerged in Miguel Gonzalez's laundromat. They terrorised several neighbourhoods in Brooklyn, attacking Gabby Gonzalez, making Cindy Wu their host and causing an advisory to stay home on the local NY1 news. The Tenth Doctor defeated them with Gabby's help in the final face-off at Green-Wood Cemetery. (COMIC: Revolutions of Terror)

Behind the scenes

 * The name of the species means "feeding on " or, slightly simplifying, feeding on higher brain functions.
 * The name is first used by the Tenth Doctor. It is most likely that he invented a name for them like he did with Pranavores because he never encountered Cerebravores before and they themselves did not use this name. However, the origins of the name are not stated explicitly.
 * Cerebravores were featured and named in the third of the three issues of the comic story Revolutions of Terror alongside the Doctor and Gabby in the gallery of three main characters of the story. (The second issue featured a human possessed by a Cerebravore and did not give their name in the gallery.)