King Ghidorah is one of the main villains of the Godzilla franchise. He is an alien hydra kaiju with three heads that have their own personality. He is also Godzilla's arch-nemesis. In the Monsterverse, he is also the biggest threat to Godzilla's title of king of the monsters. Throughout each timeline, King Ghidorah has always lost to Godzilla, especially when Godzilla has help from other kaijus, like Mothra and Rodan. Also, in Godzilla vs. Kong (the Monsterverse remake of King Kong vs. Godzilla), his spirit is apparently what powers Mechagodzilla (the main villain of the movie), who can only be defeated by the combined forces of Godzilla and King Kong, who spent most of the movie as long-time rivals, but in the end became friends.