Monster from a Prehistoric Planet, also released as Gappa: The Triphibian Monster and Gappa: The Colossal Beast debuted in Japan in 1967 under the title 大巨獣ガッパ (Daikyoju Gappa).
Gappa was a popularly syndicated “weekend movie” and “late night thriller” in the United States, and the creatures also made a cameo in the series 4 Red Dwarf episode, “Meltdown.”