Four Headed Dog

The Four-Headed Bulldog is one of the rarest Meanies. There is only one, but it is one of the fiercest, strongest, and most fearless of them all. It is defeated when The Beatles sing "Hey Bulldog" to confuse it.
As well as four heads, the dog also has at least eight legs. However, it has only the one body.
==Background==
The Four-Headed Dog somewhat resembles Kerberos (Κέρβερος), the three-headed dog who in Greek legend guards the gate to Hades to prevent any of the dead from escaping back to the living world. Kerberos' name is usually these days mangled to the pseudo-Latin form "Cerberus", similarly to Herakles being called "Hercules" or Kongzi "Confucius"; as is definitely the case with Kongzi, we probably have the Jesuits to blame for this.