King Ghidorah, also simply known as Ghidorah and dubbed as Titanus Ghidorah, is the main antagonist of the 2019 MonsterVerse film Godzilla: King of the Monsters and the overarching antagonist of its 2021 sequel Godzilla vs. Kong.
He is a malevolently extraterrestrial three-headed draconic Titan who invaded the Earth in the ancient past and clashed with Godzilla and his sidekick Mothra, who succeeded in sealing him away beneath the Antarctic ice. The organization Monarch discovered Ghidorah's resting place in 2016, and established Outpost 32 to study him, dubbing him as "Monster Zero". He is also Godzilla's arch-nemesis.
In 2019, the eco-terrorist Alan Jonah, working alongside Monarch defector Dr. Emma Russell, unleashed Ghidorah from his frozen prison in an attempt to release all of the Titans to restore the natural order. But Jonah and Russell had absolutely no idea what Ghidorah was truly capable of, and as an invasive species, from another planet, Ghidorah had no interest in restoring balance and resumed annihilating the global ecosphere, awakening all of the other Titans himself and bending them to his will. Assisted by Monarch, Godzilla and Mothra joined forces and engaged Ghidorah in Boston for a final confrontation. Ghidorah summoned Rodan, whom he had previously enslaved, to his aid to deal with Mothra, while he overwhelmed Godzilla in one-on-one combat. After defeating Rodan, Mothra sacrificed her life to empower Godzilla reinvigorating him with her energy and allowing him to finally destroy Ghidorah once and for all. With his arch-nemesis vanquished for good, Godzilla took his place as the King of the Monsters, ending the rampages of the Titans previously under Ghidorah's control.
Years later, in 2024, Ghidorah's severed left head's skull was used to control the mecha-Titan Mechagodzilla, with his consciousness later taking over the mecha. Thankfully, his short-lived reign of terror was stopped by Godzilla and King Kong.