Face Hugger

Give us a kiss!

The Face Hugger, as the name implies, is a creature that preys on other species, usually humans, by attaching itself to their face. What it does to you from there depends on the creature and how it operates. Some take over your body or mind in some fashion. Some drain you of blood or Life Energy. Some eat your brains. Some transform you in horrific fashion. And some will give you a Face Full of Alien Wing-Wong.

Examples:

The Trope Namer and Trope Maker (if not Ur-Example) is the crab-like impregnator from Alien. Many later examples are homages.

The dreamcrabs in the Doctor Who episode "Last Christmas" attach themselves to their victims' faces and slowly eat their brains, while trapping them in dreams. One of the crew even lampshades the situation as being right out of Alien.
The Doctor: There's a horror movie called Alien? That's really offensive. No wonder everyone keeps invading you.
The giant spiders contained in the Box of Gavrok in Buffy the Vampire Slayer attach themselves to people's faces before killing them.

The Face Sucker in Munchkin.
Facebiter squigs in Warhammer 40,000 bite... faces. The orks naturally find this hilarious, and often get in contests to see which will bite the other's face off first. The actual Xenomorph stand-ins use an ovipositor to perform the Orifice Ivasion instead.
- The Tyranids have a variant species of Ripper called a Cortex Leech. They leap onto a person's face then use a variety of pointed tendrils to penetrate the mouths, eyes, nose, ears, or any other available orifice and drive them into the brain, where they can then hijack the motor functions and turn them into drooling thralls to the Hive Mind.

Metroids, although more often than not they latch onto the whole head.
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.
The Protozoid Slimers from Duke Nukem 3D.
The Lifters and Diamond Claws from the Descent series behave similarly. While most of the other robots shoot at you, these enemies ram into your ship and inflict damage with their reinforced claws.
- The E-Bandits use a similar point-blank attack, only they drain your ship's energy instead of your shields.

Psi-Ops: The Mindgate Conspiracy: The Aura Beasts come of nowhere and wrap around Nick's face. Oh, and the only way to see them coming is using the psi draining Aura Vision.
Space Quest
- In Space Quest III: The Pirates of Pestulon, at Fester Blatz's World O' Wonders on Phleebhut, the postcard for Achoron shows a face hugger hugging somebody's face.
- In Space Quest V: The Next Mutation, Spike, the acid-squirting face hugger, later dubbed Spikette, spawns lots of little face huggers. The manual shows the design team being inspired by an Alien face hugger model.
- In Space Quest VI: Roger Wilco in The Spinal Frontier, when examining the ship in shuttle bay, the narrator claims the ship is "probably carrying a half-dozen miniature face-hugging saliva-dripping face-eating exo-skeletal alien piranha things."

In Campus Safari, Chrome's miniwhip Aurla does a good impression of one. (Played for laughs)
Cross Time Cafe: Sam Starfall pulls one of these off in an early strip. Hortmage finds it irritating and, maybe, disgusting.
Edward's monster in Monster Pulse. It helps that it's actually his face.
In Zero Percent Discount, a Banana Peel turns into a facehugger.
In Savestate, Rick is subjected to this by Ness, much to his irritation and, apparently, Nicole's amusement.