Ishiro Serizawa: “A false king.”

Rick Stanton: “An invasive species. That could explain how he's creating these massive storms and the effect he's having on the other Titans. It's almost like he's reshaping the planet to his own liking.”

Ishiro Serizawa: “These legends, what did they call him?”

Ilene Chen: “Ghidorah. The one who is many.”

― Dr. Rick Stanton, Ishiro Serizawa, and Ilene Chen as they uncover King Ghidorah’s origin (Godzilla: King of the Monsters)

An evil alien dragon who invaded Earth in the ancient past, King Ghidorah clashed with Godzilla and Mothra, who succeeded in sealing him away beneath the Antarctic ice. The organization Monarch discovered Ghidorah's resting place in the present day, and established Outpost 32 to study him, dubbing him "Monster Zero." In 2019, the eco-terrorist Alan Jonah, working alongside Monarch defector Dr. Emma Russell, unleashed Ghidorah from his frozen tomb in an attempt to release all of the Titans to restore the natural order. Being an invasive species, Ghidorah had no interest in restoring balance and resumed annihilating the global ecosystem, 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 to his aid to deal with Mothra, while Ghidorah overwhelmed Godzilla in one-on-one combat. After defeating Rodan, Mothra sacrificed her life to save Godzilla from Ghidorah, reinvigorating him with her energy and allowing him to finally destroy Ghidorah once and for all. With the three-headed terror finally vanquished, Godzilla took his place as the King of the Monsters, ending the rampages of the Titans previously under Ghidorah's control.

Following the three-headed monster's death, Jonah purchased a head Godzilla had severed from Ghidorah in Isla de Mara from a group of fishermen. The skull was eventually sold to Apex Cybernetics, who used it as part of the control system for Mechagodzilla. After the mecha was powered by an untested power source from the Hollow Earth, King Ghidorah's lingering consciousness merged with Mechagodzilla's A.I., driving it berserk. After killing its creators, the rogue Mechagodzilla began a rampage in Hong Kong, though it was eventually destroyed by the combined efforts of Godzilla and Kong, ending Ghidorah's brief resurgence.