A headcrab is a fictional alien parasitoid first appearing as an enemy in Valve's 1998 video game Half-Life, as well as in subsequent games in the Half-Life series. Attributes Depiction In-universe, headcrabs are parasitic life forms, measuring about in length. The "common" headcrab variant has a rounded body with four legs for movement: two long, clawed legs at the front and two short legs at the back. Their pair of large frontal claws are frequently utilized in their attacks, and as additional support when standing still. Under the headcrab's body is a large, rounded mouth surrounded by mangled, rigid flesh with a sharp claw-like beak. Physically, headcrabs are frail: a few bullets or a single strike from the player's melee weapon are sufficient to kill them. They are also relatively slow-moving, and their attacks inflict very little damage. However, they can leap long distances and heights. Headcrabs seek out larger human hosts, which are converted into zombie-like mutants that attack any living life form nearby. The converted humans are more resilient than an ordinary human would be and inherit the headcrab's resilience toward toxic and radioactive materials. Headcrabs and "headcrab zombies" can also catch fire. The games establish that while headcrabs are parasites that prey on humans, they are the prey of the creatures in their homeworld. Bullsquids, Vortigaunts, barnacles, and antlions eat headcrabs. Vortigaunts can be seen cooking them in several locations in-game. Variations While the original Half-Life only included one type of headcrab, as well as baby headcrabs, Half-Life 2 introduced two major variations: a faster variant, and poison headcrabs. Headcrab zombies also receive these variations in Half-Life 2. Gonarch In-universe, the Gonarch is a tall, heavily armored version of a headcrab that appears only once as a boss fight near the end of Half-Life in Xen. The Gonarch appears to function as a hive queen, endlessly spawning infant headcrabs from a bulbous fleshy sack located on its underside. Unlike other types of headcrabs, the Gonarch lacks a mouth on its underside, suggesting it is unable to zombify a host. It was explained by the Half-Life team that the creature was based on the idea of “What if we put a giant testicle on a 20-foot-tall, armored spider?” which may be its namesake, a combination of gonad and monarch. Fast headcrab In-universe, the fast headcrab is a speedier, arachnid-like version of the ordinary headcrab. Its skin is lighter,