Baragon, a dinosaur who survived mass extinction by embracing a subterranean environment and shifting its natural biorhythms to a nocturnal pattern, was a creature completely unknown to humankind until the mid-20th century. Attracted by the noise of an offshore oilrig, Baragon attacked the unsuspecting facility. The burrowing behemoth did not reveal himself again until he attacked Shirane, a small town in the Japanese countryside. Since both of Baragon's attacks were in the dead of night and his identity was not yet confirmed, these incidents were blamed on an escaped, heavily mutated humanoid known as Frankenstein.

More disasters followed, and one morning when there was enough fog permeating the air for him to tolerate the sunlight, Baragon attacked a small farming community. The Japanese Self-Defense Force blamed Frankenstein once again for the terrifying event, but one witness from the oilrig disaster convinced three scientists that it was in fact another monster. As the scientists attempted to locate Frankenstein, an explosive was set off and an angry Baragon emerged from underground. Frankenstein arrived just in time, and the two monsters clashed. Baragon was ultimately forced to retreat.

Desperate for food, Baragon spotted an evacuating village. Before he could make his move, Frankenstein caught up with him and the two monsters began to fight to the death! Frankenstein outsmarted and outmaneuvered Baragon, but Baragon's fiery breath gave birth to a raging forest fire. Frankenstein eventually choked his foe into submission, and the mighty dinosaur was no more. Unfortunately, shortly after the confrontation a large fissure opened beneath the two giants, sending them plummeting into the chasm below.

Contained in the zoological preserve known as Monsterland on Ogasawara Island, a smaller Baragon was found living amongst the island's inhabitants near the dawn of the new century. Unfortunately, the creature's relatively peaceful life was interrupted by the Kilaak alien invasion. Along with his fellow monsters, Baragon was sent to destroy the capital cities on Earth in order to enact the diabolical schemes of the invading extra terrestrials. In the ensuing chaos, the Earthlings managed to regain control of the monsters, and Baragon was ordered to destroy the Kilaak base near Mount Fuji. He merely watched, however, as Godzilla, Minilla, Rodan, Gorosaurus, Anguirus, Kumonga and Mothra were dominating the fight against the newly arrived King Ghidorah. Following the Kilaaks' permanent defeat, Baragon returned to Monsterland, where he lived out the rest of his days in peace.