Monster X

Monster X, later known as Keizer Ghidorah in his transformation, is one of the monsters under Xilien control and one of Godzilla's strongest enemies.

History
Monster X was brought to Earth in the Gorath asteroid by the Xiliens when their invasion was going downhill as a result of Godzilla's interference. Monster X battled against Godzilla and proved a powerful foe, until Mothra arrived to help Godzilla. Unfortunately, the Xiliens sent a repaired Gigan to aid Monster X and Mothra was knocked unconscious. The two titans overpowered the King of the Monsters. Godzilla was at a disadvantage until Mothra regained consciousness and battled Gigan. Mothra was set on fire but used this to end the fight by ramming her body into Gigan, leaving Gigan dead and Mothra heavily injured.

Godzilla and Monster X continued fighting, with Godzilla finally gained the upper hand against Monster X. Monster X fired his Gravity beams while Godzilla fired his atomic ray. The beams clashed against each other and sent the two monsters flying away. Godzilla got up to see Monster X go through a startling transformation. He got down on all four and started sprouting wings, his white, skeletal armor changed into a dark gold armor, and his shoulder skulls enlarged into extra heads. Monster X had transformed into Keizer Ghidorah.

Keizer Ghidorah
Godzilla was about to attack when Keizer Ghidorah fired his gravity beams and knocked Godzilla to the ground. Godzilla was knocked through the city and Keizer Ghidorah bit into Godzilla's skin, sucking out his life force. It appeared Godzilla would soon by dead and Earth would suffer at the claws of Keizer Ghidorah.

Fortunately, humankind helped. The Gotengo fired the ray of Keizer, which would give whoever possessed it extraordinary abilities. Godzilla was hit by the ray and his power increased. He freed himself from Keizer Ghidorah grip and fights back, gaining the upper hand by destroying his middle head and fired Keizer's own Gravity beams on himself, heavily injuring him. The creature was then sent flying through the air and into space, and Godzilla fired a hyper spiral ray, destroying Keizer Ghidorah. The space demon blew up into a million peaces, and Godzilla gave a victory roar.