King Ghidorah is a fierce, golden dragon with three heads who has been one of Godzilla's most persistent foes.
Feared throughout the cosmos as the destroyer of worlds, Ghidorah wiped out the advanced civilization of Venus thousands of years prior to his arrival on Earth. His appearance on Earth was heralded by a surviving Venusian who took over the body of Princess Selina Salno, and he crashlanded in a magnetic meteor. Soon the meteor cracked open, unleashing Ghidorah upon Japan. After a brief rampage however, he was defeated by the combined might of Godzilla, Rodan and Mothra, who forced him to retreat back into outer space.
Sometime later, Ghidorah found his way to Planet X, where he was brought under the control of the Xians, who dubbed him "Monster Zero." Intending to use him as well as Godzilla and Rodan to conquer the Earth, the Controller of Planet X lied to astronauts Frank Glenn and Ken Fuji, having Ghidorah attack Planet X's cities on purposes and making it seem as if the Xians were in dire need of help from the Earthlings. With Earth's permission the Xians brought Godzilla and Rodan to Planet X where they "defeated" Ghidorah. However soon they too were brought under the Xians' control and all three monsters were unleashed upon the Earth.
Ultimately Glenn, along with inventor Tetsuo Teri, discovered that the Xians and their technology were susceptible to magnetic wavelengths. Dr. Sakurai and Fuji therefore devised a means of disrupting the Xians' controls using powerful magnetic waves. This killed the Xians (by blowing up their saucers) and severed the aliens' hold on all three monsters. Left to their own devices, the three monsters battled. Again Ghidorah was defeated and fled into outer space.
Thereafter the once feared and majestic monster would be reduced to being a slave for different alien races, each out to conquer the Earth for their own aims: first alongside Gigan by the cockroach aliens from Nebula Space Hunter M, wherein he was repelled by Godzilla and Anguirus, and finally in 1999 by the Kilaaks.
It was whilst under Kilaak control that Ghidorah would ultimately meet his demise. After Earth's monsters were released from their control, the Kilaaks sent Ghidorah in to fight Godzilla in a last ditch effort to take the planet. Ghidorah found himself up against Godzilla, Rodan, Anguirus and Mothra once more, as well as Godzilla's son Minya, and Kumonga and Gorosaurus as well. The combined might of so many monsters resulted in a humiliating defeat and finally death for Ghidorah.
King Ghidorah was created in a plot concocted by Chuck Wilson to destroy Japan and thus prevent it from becoming an economic superpower in the future. Wilson's associates Emmy Kano and the android M-11 went back in time to Lagos Island in the year 1944 to remove the Godzillasaurus that would eventually become Godzilla, and replace him with three dorats. Thus when atomic testing was conducted on the island, the dorats, not Godzilla, became irradiated, and mutated and combined into a single creature, which Wilson named "King Ghidorah." Ghidorah subsequently took Godzilla's place in 1992 and terrorized Japan.
Controlling Ghidorah from his spaceship-time machine, Wilson used Ghidorah to raze Japan. However, Godzilla was recreated again due to an accident involving a nuclear submarine, and reappeared in Japan to do battle with Ghidorah. Kenichiro Terasawa was able to persuade Emmy to turn against Wilson, and, with the help of a reprogrammed M-11 they sabotaged Wilson's ship, which was destroyed by Godzilla. With Wilson's hold over Ghidorah broken, the mutated three-headed monster became confused and left himself open for attack. Godzilla blasted off one of Ghidorah's heads with his atomic breath, and the mortally wounded dragon fell into the sea.
With the threat of Godzilla still looming, however, Emmy and M-11 took a spare time machine and returned to the future, where they recovered the corpse of Ghidorah. The scientists of their time were able to rebuild Ghidorah into a cyborg, turning him into Mecha-King Ghidorah. The cyborg Ghidorah was then sent back in time to 1992 to do battle once more, this time on the side of good.
King Ghidorah was one of three Guardian Monsters that protected Japan from attack. He was the God of Air and was the most powerful of the three.