Argon (Godzilla: New Age of Monsters)

Argon is an alien Kaiju who first appeared in the Godzilla: New Age of Monsters/Avengers Assemble crossover special, Avengers vs the Gammas.

Origin
According to Alien Shamer, Argon is a space monster who invades other planets.

History
Alien Shamer shows them live footage of Argon heading towards Earth in his saucer form and arrives on Mount Fuji when Godzilla arrives to challenge the space monster as the King of the Monsters successfully manage to overpower Argon as the space creature was forced to retreat and fled Earth after transforming back into a UFO.

Trivia

 * Argon is a Kaiju from Ultraman 80.