Godzilla has long been portrayed as a nearly unstoppable force - hence the title "King of the Monsters" - but he secretly has a deadly weakness. Godzilla vs. Mechagodzilla II reveals that Godzilla has two brains, one one of them is in the most unusual place, which is the key to killing the Titan (and not the oxygen destroyer, which was only capable of killing the 1954 Godzilla).
True to the spirit of Godzilla, Legendary's MonsterVerse has depicted Godzilla as the alpha predator, but with a new twist on the classic formula. This version of Godzilla is seen as a force of nature, and an overriding theme in the MonsterVerse is that nature always wins. Godzilla's prowess was on full display when he defeated two M.U.T.O.s in the 2014 movie, and he'll get another chance to exert his dominance when Godzilla: King of the Monsters pits him against his classic nemesis, King Ghidorah, along with Rodan and Mothra. When the four meet in battle, the real King of the Monsters will stand revealed.
While Godzilla is a somewhat heroic figure in the MonterVerse, this wasn't the case for Toho's Godzilla, at least not in the 1990s. Released in 1993, Godzilla vs. Mechagodzilla II saw Godzilla looking for his son while clashing with Rodan and Mechagodzilla, who was built by the humans to save Japan. After studying Baby Godzilla's anatomy, the military discovered a way to beat Godzilla. As it turns out, Godzilla has a second brain, which is located where his tails meets his torso. This brain is what controls Godzilla's movement. Mechagodzilla was equipped with a harpoon-like weapon that could pierce Godzilla's muscle tissue and destroy the brain by blasting it with electricity.
Mechagodzilla was successful, with its attack leaving Godzilla paralyzed. Godzilla would have been killed if Rodan hadn't sacrificed himself by giving Godzilla his energy; this reconstructed the second brain and saved Godzilla's life. What happened to Godzilla is further proof that even the King of the Monsters isn't indestructible.
Though the second brain nearly led to Godzilla's death, humanity never attempted to exploit this weakness again, though this could be because the opportunity never presented itself. Two years later, after gaining his burning form, Godzilla died in his battle with Destoroyah. It's unclear if later versions of Godzilla, such as the one that debuted in Godzilla 2000, had the same weakness as his predecessor. As for Legendary's Godzilla, it remains to be seen if this obscure fact about Godzilla's anatomy will be translated to the MonsterVerse.
