Rhedosaurus is a giant carnivorous man-eating monster lizard/giant dinosaur and the main antagonist of the 1953 film, The Beast From 20,000 Fathoms.


Rhedosaurus was one of the last surviving members of his species, awakened by a nuclear test in the Arctic. He is 200-ft (61 m) long. He made his way down to the North American coast, destroying everything in his path and ending up in New York, his original home. He was released from his frozen, hibernating state by an atomic bomb test in the Arctic Circle. He was thawed out of the ice where he had been held in suspended animation for millions of years. He sinks a fishing ketch off the Grand Banks, destroying another near Marquette, Canada, wrecking a lighthouse in Maine and destroying buildings in Massachusetts. His enemies, the soldiers who attempted to kill him were complicated, because of the ancient disease he carried; spilling his blood that can make people sick and die with an illness feeling while the plague from his blood has freed, which was almost as deadly as a dangerous venomous creature himself. He bleeds all over the streets of New York, unleashing a horrible, virulent prehistoric contagion, which begins to infect the populace, causing even more fatalities. The infection precludes blowing him up or even setting it ablaze, lest the contagion spread further. It is then decided to shoot a radioactive isotope into the his neck wound with hopes of burning him from the inside, killing him without releasing the contagion. When he comes ashore and reaches Coney Island's amusement park, military sharpshooter Corporal Stone takes a rifle grenade loaded with a potent radioactive isotope and climbs on board a roller coaster. Riding the coaster to the top of the tracks, so he can get to eye-level with the beast, he fires the isotope into his open neck wound. He thrashes about in reaction, causing the roller coaster to spark when falling to the ground, setting the amusement park ablaze. With the fire spreading rapidly, the park becomes completely engulfed in flames. Rhedosaurus was eventually killed at Coney Island when a radioactive isotope was shot into his wound on his neck, fatally wounding him and also neutralizing the disease he carries. The radiation also incinerated him to death with a dying scream onto the ground, dead, while the island is still burning.


  • The scene where Rhedosaurus destroys a lighthouse was based on the short story, The Fog Horn.
  • The Rhedosaurus was one of the main inspirations for Godzilla, along with King Kong.
  • The Rhedosaurus puppet was used again in the film, Planet of the Dinosaurs where it played Rhedosaurus again who was doomed to be killed by the Tyrannosaurus Rex.
  • Rhedosaurus also appeared in the 6th episode of the 2nd Season of ABC's, Whose Line Is It Anyway?.