The Chimera was a human spliced with alien DNA. It induced a primal fear in those who encountered it. Its basic form looked like a human with incredibly damaged, grey skin. However, it only appeared to operate in this guise when no one was watching. Once, it took on the shape of a black goblin with red eyes (to Jack Harkness), a zombie clown (to Gwen Cooper), a bearded man in a trench-coat (to Jack Harkness), a deceased piano teacher (to Owen Harper) and an approximation of a Cyberman (to Ianto Jones).