A parasite that will get on a person's head, open its mouth, and slide itself down onto the person's head, taking control of their body. They are capable of speech and eager to talk with you. They are friendly but still will request to take control of your body. If allowed to, they will first get onto the persons head, then suck themselves down, completely covering the persons head. The headcrab then pilots the person, mutating their body into a head-crab zombie.