Is the monster Godzilla based on an old myth/legend?

Question

In the 1998 Roland Emmerich-directed film Godzilla,* a Japanese sailor who survived an attack by the monster early in the film identifies the creature as "Gojira."

Later in the film, news reporter Charles Caiman (played by Harry Shearer) reports on this, where he translates that name into English as "Godzilla," and proceeds to explain [emphasis added]:

Godzilla. That's what Japanese sailors called him in song. A mythological sea dragon that filled their hearts with fear.

While I am aware that Godzilla was created in a post-WWII era Japan (having experienced a massive amount of destruction from the deployment and detonation of two nuclear bombs by the U.S.) and that the subject of nuclear weapons was incorporated into the story and the character (such as with his atomic breath), I'm curious if there is anything to suggest that the monster (or at least its name) was also based on or inspired by an older legendary or mythological creature? Or was this just a case of the writer/director taking liberty with the material for the sake of worldbuilding and creating an in-universe explanation for the origin of the name attributed by the Japanaes sailor to the monster?

||

*Note: I'd like to point out that I'm aware that the 1998 film is not well-regarded by fans and has been denounced by Toho (the studio that created and owns the rights to Godzilla), to the point where the film's monster is now officially known as simply "Zilla" instead of Godzilla (in reference to Toho's harsh criticism that the film "took the 'God' out of 'Godzilla'").

Answer 1

Godzilla (aka Gojira) was designed in 1954 by Teizo Toshimitsu and Akira Watanabe under Eiji Tsuburaya's supervision.

The first draft of the original 1954 Godzilla movie was simply called "Development Plan G", the "G" standing for "Giant". Toho held a contest to name the monster, and the "Giant Monster" of "Development Plan G" was eventually named Gojira, a combination of the Japanese words gorira (gorilla) and kujira (whale).

Because of the name Gojira, early designs were gorilla-like or whale-like, before they settled on the dinosaur-like design we know and love today, specifically combined elements of a Tyrannosaurus, Iguanodon and the dorsal fins of a Stegosaurus.

So I'm sorry to say that Godzilla was not based on any mythological creature, but was built up over a number of months, going through many iterations until we got our beloved radioactive reptile. The mythos of Godzilla came in later movies, after the original movie became successful in the US.