Simple. It attaches itself to someone's face.
Usually Nightmare Fuel
from some horror film.
May be related to Face Full of Alien Wing-Wong
. See also Orifice Invasion
, Personal Space Invader
- The mind-control starfish of Starro the Conqueror.
- The xenomorphs from Alien. Many later examples are homages.
- Gligar and Gliscor from Pokémon.
- Headcrabs from the Half-Life saga.
- Brainsuckers from X-COM Apocalypse, which are used as ammunition by certain aliens in addition to appearing on their own. Replacing a person's brain is their entire purpose; They don't even have a digestive system.