WARNING: The following contains spoilers for Godzilla vs. Kong, now in theaters and streaming on HBO Max.
Perhaps the highlight of Godzilla vs. Kong isn't the clash between the title monsters, but instead the introduction of the MonsterVerse's version of another classic kaiju. MechaGodzilla has been around since the original Godzilla movie series, and he's since become Godzilla's fiercest foe besides King Ghidorah himself.
The new version of MechaGodzilla bears a different, slightly thinner framed design than normal, but that's not the only change from the character's original incarnation. This MechaGodzilla has a vastly different origin than the original, though this backstory does resemble another version of the mechanical monster. Here's how the different versions of Godzilla's technological doppelganger compare to each other.
Showa MechaGodzilla
MechaGodzilla's debut was in the eponymous 1974 film, Godzilla vs. MechaGodzilla. It and its follow-up were the final entries in the original Showa era continuity, making MechaGodzilla the final archenemy of that Godzilla. He was created by aliens from Black Hole Planet 3, who secretly had ape-like forms. They sought to conquer Earth in lieu of their planet's impending destruction, using MechaGodzilla as a weapon to do so. Initially wearing a layer of fake organic skin and masquerading as the real deal, MechaGodzilla is soon revealed as a robot and manages to defeat the real Godzilla.
The alien robot is destroyed when Godzilla decapitates it, but returns in 1975's Terror of MechaGodzilla. There, his life force was connected to a woman whom the aliens had abducted and turned into a cyborg. When she dies, Godzilla uses his atomic breath to destroy the robot once and for all.
Heisei MechaGodzilla
MechaGodzilla has a much more terrestrial origin in the Heisei era. This version was made by the Japanese military in order to combat Godzilla, though he's tied to another kaiju entirely. MechaGodzilla was created from the remains of the cyborg Mecha-King Ghidorah, who had been killed in the film Godzilla vs. King Ghidorah. This version was able to almost completely overpower and take down Godzilla. In fact, it was only the sacrifice of the already-dying Rodan, who gave Godzilla a new fire-based attack, that was able to take the robot down.
This MechaGodzilla also had a form called Super MechaGodzilla, which gave him a jetpack and back-mounted missile launchers when he combined with a small ship called the Garuda.
MonsterVerse MechaGodzilla
The MonsterVerse also does away with the alien origin for the character, using a premise more based on the Heisei incarnation. This MechaGodzilla was built out of the remains of King Ghidorah, just like the Heisei version, with the intent of giving Apex Technologies a weapon with which to combat and destroy Godzilla and all the other Titans. Just like in Godzilla vs. MechaGodzilla II, he's only defeated by Godzilla teaming up with another kaiju, in this case a brutally beaten Kong.
Basing the story off of that version of MechaGodzilla instead of the original definitely makes more sense. For one, introducing aliens into the MonsterVerse would have been ridiculous and possibly continued the bloated storytelling of King of the Monsters. Likewise, the presence of goofy ape aliens even in the Showa era was a representation of how silly and cartoonish the series had become by that point, and it's no wonder that they figure into the ending for the Showa era. Thankfully, this MechaGodzilla is as terrifying and powerful as his name would suggest.
Directed by Adam Wingard and written by Eric Pearson and Max Borenstein, Godzilla vs. Kong stars Alexander Skarsgard, Millie Bobby Brown, Rebecca Hall and Brian Tyree Henry. The film is in theaters and on HBO Max now.