Four Godzilla species of the Monsterverse. Yes, although they might not be the Godzilla we know, the other three either share a common ancestor or are a separate species of a Godzilla genus.
The ancient skeleton was originally worshipped as a god by numerous ancient peoples that encountered him, like the Biblical Dagon by the Phoenicians and the lightning god Raijin by the Japanese, according to Godzilla: Aftershock.
The Hollow Earth Lizards are believed to be an offshoot species of the Titanus Gojira evolutionary lineage in the artbook Godzilla vs. Kong: One Will Fall: The Art of the Ultimate Battle Royale, with the lizards’ jagged dorsal plates and general look being markers of this kinship.
Mega Gojira, the one that was seen as a skeleton killed by ancient Kongs in their throne room.
And then of course we have Godzilla, which we all know by now. This King of the Monsters has been around for millions of years and after every nuclear boost, he grows in size and also his dorsal plates change and evolve in accordance to the environment and threats.

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