Ghidorah (Ghidrah, Ghidora, King Ghidorah, the three-headed monster, Monster Zero) is a fictional three-headed dragon-like monster featured in several Godzilla films. It is often depicted with two wings, two feet, three heads and a tail. It always appears as an antagonist to Godzilla and Earth at large. Originally it arrived by a magnetic meteorite before being repelled into space (proving it can survive in a vacuum). Aliens return with Ghidorah as their mind controlled slave. Its havoc is again stopped, even killing the creature in the 1968 movie.

The monster returns in several resurrected forms thereafter.