A cockatrice is a mythical beast, a two-legged dragon with a rooster's head, bearing a crown. The terms "cockatrice" and "basilisk" are often used interchangeably. The cockatrice was first described in its current form in the late twelfth century. According to Alexander Nickham’s 1180 text, De naturis rerum, the cockatrice was supposed to be born from an egg laid by a cock and incubated by a toad. The cockatrice was reputed to have magical abilities, including turning people to stone or killing them with a look or a breath. It was believed that a cockatrice would die instantly upon hearing a rooster crow, or on looking at itself in a mirror.
In England the town most associated with the cockatrice is the village of Wherwell, near Andover in Hampshire. The story goes that the cockatrice terrorised the village until it was imprisoned in the dungeons below Wherwell Priory. A prize of land was offered to anyone who could kill the creature. None was successful until a man named Green lowered a mirror into the dungeon. The cockatrice battled against its own reflection until exhausted, at which point Green was able to kill it.