Godzilla is confirmed to have been the original king of the monsters in the MonsterVerse franchise, which is evident in the Godzilla: King of the Monsters movie. Warner Bros. and Legendary's MonsterVerse delivered a sequel to Gareth Edwards' 2014 Godzilla reboot earlier this year - after first expanding the shared universe with Jordan Vogt-Roberts' Kong: Skull Island in 2017 - which not only brought back the titular Titan but also introduced iconic kaiju Mothra, Rodan, and Ghidorah, as well as a handful of other in-universe monsters.
Given that Ghidorah was the alpha for most of Godzilla: King of the Monsters and how all of the other Titans gravitated towards him, it was believed that Ghidorah had always been the king of the monsters in this universe. However, that may not have been the case, at least not entirely. Ghidorah's origin story in the MonsterVerse made the alien creature a force to be reckoned with. And at some point, the three-headed dragon must have been defeated because Ghidorah was stuck in Antarctica until the sequel's story began. We now know why.
It was theorized prior to Godzilla: King of the Monsters' release that Godzilla and Ghidorah had fought before and that their faceoff in the sequel was actually a rematch. As it turns out, that is true. Godzilla: King of the Monsters director Michael Dougherty confirmed on Twitter that Godzilla defeated Ghidorah before, which is why the alien was buried underneath the ice in Antarctica at the start of the film. What's more, Dougherty also says that Godzilla could've beaten Ghidorah if it wasn't for the humans interfering (with the Oxygen Destroyer).
Godzilla's ancient battle with Ghidorah was first teased in the Kong: Skull Island post-credits scene, when Monarch scientists Houston Brooks (Corey Hawkins) and San Lin (Jing Tian) showed James Conrad (Tom Hiddleston) and Mason Weaver (Brie Larson) files they had on other creatures in the MonsterVerse - the last of which was a painting of Godzilla fighting Ghidorah.
That painting could very well have been the depiction of Godzilla and Ghidorah's original battle, which Dougherty suggests, but then again, it could also be a visualization of a story that was passed down through generations. In the end, that painting was most likely Legendary's way of teasing the future without writing themselves into a corner. After all, who would have been around in Antarctica to witness a battle of this scale and survive?
Regardless, it seems Godzilla remains undefeated in the MonsterVerse and is truly the king of the monsters (or alpha predator). Now it's a matter of retaining the crown when Adam Wingard's Godzilla vs. Kong releases in theaters in 2020, since the iconic kaiju is slated to go up against Kong, the king of the primates - and one of them will lose.
