A five-headed snake is a fictional legless reptile. It consists of a long torso with a single tail and five snake heads. There are stories in Chinese, Hindu and Greek mythologies of five-headed cobras, but in modern times there are no credible reports of such a creature.
Polycephaly describes animals with multiple heads. Although two and even three headed-snakes have been verified, five-headed snakes have not. The chances of survival decrease significantly when there's more than a single head present, and two-headed snakes have been known to kill each other. When three heads are present, the third head is usually deformed and largely unresponsive.