Barugon

After a group of treasure hunters ventured into the forbidden Valley of Rainbows in New Guinea, one of them brought a giant opal with him back to Japan, not knowing the precious stone was actually the egg of Barugon. After being unintentionally incubated by an infrared lamp, Barugon hatched from his egg and came ashore in Kobe, tearing the city apart with his extending tongue and rainbow death ray and freezing entire blocks with the chilling liquid released from his tongue. Barugon reached Osaka and confronted Gamera, and defeated him after freezing him solid. After withstanding multiple failed attempts by the JSDF to destroy him, Barugon was attacked by Gamera once again, this time being dragged to the bottom of a lake to his death. In Gamera: Super Monster, Barugon was resurrected by the evil space criminal Zanon to fight Gamera, but was defeated once again.

Introduced in the second film of the Gamera series, Barugon was Gamera's first-ever opponent. Though he never returned in a film outside of stock footage, he was featured in a manga adaptation of his debut film published by Kadokawa in 2002, which placed its events into the continuity of the Heisei trilogy, between Gamera 2: Attack of the Legion and Gamera 3: Revenge of Iris.