Headcrabs are an enemy in the Half Life series of games. It is a parasitic creature about the size of a house cat, with four clawed legs. They are fairly slow when walking on the ground, but their leaping attack is very dangerous, especially when headcrabs hunt in packs.
Headcrabs first appeared after the Black Mesa Research Facility experienced a resonance cascade during a scientific experiment. They could be found roaming the facility looking for prey. They could also be found perched atop the heads of human beings. The headcrabs are able to take control over the movement of their victim, turning them into a " headcrab zombie." It is unclear how much control a headcrab has over its victim's mind, as headcrab zombies can often be heard laughing evilly when attacking, but also sceaming in pain and pleading for help when shot.
Half Life 2 introduced a variant of the headcrab known as the poison headcrab. Poison headcrabs have a black skin, are faster and attack more viciously, and are also able to inflict a deadly poison via their bite. Dr. Kleiner's pet headcrab Lamarr is de-beaked and eats watermelons, yet still finds ways to mischievously meddle in his experiments. Despite their name, resistance fighters in City 17 have commented that headcrabs do not really taste at all like crab.
There are 3 flavours of Headcrab,There are Standard Headcrab, Fast Headcrab and Poison Headcrab.
Standard Headcrabs are cream colored, have thick limbs and, as of Half Life 2: Episode 1, can latch onto 2 different enemies to form zombies, known as Standard Zombies (made up of resistance members) and Zombines ( Combine forces) They are plentiful in number, but are not very dangerous by themselves.
Fast Headcrabs look similar to standard headcrabs, but have a more spider-like appearance and longer, thinner limbs, and are very fast. fittingly enough, they are the hosts of the notorious Fast Zombie, which are incredibly agile and quite frightening.
Poison Headcrabs, as mentioned earlier, are black, tarantula-like, have markings similar to the orb-weaving spider, and are considered to be the most dangerous type of headcrab. when It attacks, it is able to drop Freeman's health to 1, which regenerates slowly. when encountered by itself, this can be a useful way to recover HP, particularly if encountered with low health. however, when encountered with many enemies, it can spell instant death. They form the dangerous Poison Zombie, which house 4 poison headcrabs on its back, with up to 3 can be thrown, and has very high endurance.
Outside of Half Life
A standard headcrab is an unlockable playable character in the Steam version of Super Meat Boy. He is similar to the 360 version of Gish, sharing the ability to stick to walls and slide on ceilings, but has green blood and a different skin.