The "alpha Titan" term has never been clearly defined in Legendary's MonsterVerse, but events in alpha of the Titans, but apparently, that word can be attributed to more than one creature.
Interest in being the alpha has been the driving force before behind two of the MonsterVerse's four movies. In Godzilla: King of the Monsters, having this title had a lot to do with what made Ghidorah so threatening. Not only was he terraforming the planet, but his position as the alpha was allowing him to lord over several other Titans in the MonsterVerse at once. Years after Ghidorah's defeat launched the beginning of Godzilla's reign, the latter had to fight to keep his crown in Godzilla vs. Kong. Their battle for dominance could have culminated in a new alpha ri to take his place, but this scenario was thwarted when Godzilla emerged triumphant at the end of the movie.
The MonsterVerse's Alpha Titans Explained
While it's true that Godzilla is the current alpha of the Titans in the MonsterVerse, it's important to note that he's not technically the only creature that term fits. After all, it was already confirmed by Dr. Ilene Andrews in Godzilla vs. Kong that Kong is a "rival alpha" to Godzilla. In Legendary's Godzilla movies, an alpha is a Titan more powerful than most and a monster capable of commanding respect from the others. A monster's alpha status can be recognized by the frequency of their roar, as evidenced by the humans' attempts to create a fake alpha signal in King of the Monsters.
Only one of these alpha Titans can be known as the alpha at one time. Right now, of course, that title belongs to Godzilla, but theoretically, it could have been taken away by Kong had he won their fight in Godzilla vs. Kong's ending. Since Kong is an alpha himself, he too has what it takes to be the King of the Monsters, but earning that glory depended on him dethroning the reigning alpha, which is a feat he failed to accomplish.
Which Monsters Are Alpha Titans?
It's unlikely that Godzilla, Ghidorah, and Kong are the only alpha Titans in the MonsterVerse. It wasn't confirmed within King of the Monsters' story, but it's at least possible that both Rodan and Mothra share the same distinction. King of the Monsters director Mike Dougherty has said in the past that Rodan's power level is comparable to Godzilla's. This comment speaks volumes about the King of the Skies' untapped potential in combat. Plus, the Titan's willingness to challenge Ghidorah may be a hidden indicator of his own alpha status. He lost that fight, but it's not outside the realm of possibility that he or one of his ancestors was the alpha of the Titans in a previous era.
There's also the matter of Mothra. Whereas several other Titans quickly fell in line when Ghidorah burst onto the scene, Mothra rejected his call and stood up to him in the movie's final battle. Given that she's known as the Queen of the Monsters, it wouldn't be a surprise if she counts as an alpha. Several of the other Titans that populate the Earth could secretly be alphas as well, especially since there's so many of them. King of the Monsters described the number of known Titans at the time as "17 and counting," but several more could have been discovered since then. There's no telling how many of them are classified as alphas by Monarch.
How Godzilla vs. Kong Set Up 2 MonsterVerse Alphas
How Godzilla vs. Kong ended the conflict between the two titular monsters set up a major change in the natural order. Up until now, there could only be one Titan to rule the rest in the MonsterVerse, but the discovery of the Hollow Earth opens up a way for there to be two alphas going forward. After the fight with Mechagodzilla. Kong was relocated to the Hollow Earth world, where he claimed the throne previously occupied by his ancestors. Since Godzilla spends most his time in the ocean, the new king of the Hollow Earth doesn't have to be too concerned about his rival invading his territory. Since that's the case, Kong can be the alpha of the Hollow Earth, while Godzilla continues acting as the alpha on the surface. After Godzilla vs. Kong, each of the two Titans has their own domain to rule for the foreseeable future.