Baragon

Baragon (バラゴン Baragon) is a subterranean reptile kaiju who first appeared in the 1965 Toho film Frankenstein vs. Baragon, and later debuted in the Godzilla series in the 1968 film Destroy All Monsters.

Origins
Baragon is the descendant of a Mesozoic reptile called Baranosdragon (バラナスドラゴン Baranasudoragon) that survived into the modern day living underground.