Takehito Fujio: “King Ghidorah, who sunk in the ocean?”

Kenichiro Terasawa: “Yeah, that's right. Could you revive him with technology from the 23rd century?”

Emmy Kano: “Resuscitate him in the 23rd century, and then bring him back to the 20th century?”

Miki Saegusa: “King Ghidorah's hurt very badly. Will he survive until the 23rd century?”

Emmy Kano: “As long as his cells are still alive.”

Hironori Mazaki: “It's possible, if preserved in low temperatures.”

Emmy Kano: “Well?”

M11: “Of course, I shall do it. I exist to do so.”

― Takehito Fujio, Kenichiro Terasawa, Emmy Kano, Miki Saegusa, Hironori Mazaki, and M11 discuss reviving King Ghidorah to fight Godzilla. (Godzilla vs. King Ghidorah)

Despite its name, Mecha-King Ghidorah is not a fully mechanical robot but a cyborg; it was built in the year 2204 around the comatose body of King Ghidorah after he was defeated by Godzilla in 1992. Mecha-King Ghidorah was sent back to 1992 to battle Godzilla in Tokyo before he could destroy Japan, and succeeded in halting his rampage and dumping him in the ocean, though it was destroyed in the battle. In Godzilla vs. Mechagodzilla II, the remains of Mecha-King Ghidorah's mechanical middle head were salvaged by G-Force, who reverse-engineered its technology in order to build Mechagodzilla.