[[quoteright:214:http://static.tvtropes.org/pmwiki/pub/images/MV5BMjE5ODE1NDEzNV5BMl5BanBnXkFtZTcwMzkyNDAwMQ__V1_SY317_CR10214317__4643.jpg]]

'''''The Beast from 20,000 Fathoms''''' is a 1953 giant monster movie directed by Eugène Lourié. [[TropeMaker The film was the first giant monster movie of the '50s]], following a hiatus in the genre that had been occurring since 1933's ''Film/KingKong'', and this film also introduced the theme of the [[ILoveNuclearPower atomic bomb]] to the genre. [[FollowTheLeader It kicked off a hefty trend]], including ''Film/TheAmazingColossalMan'', ''Film/AttackOfThe50FootWoman'', ''The Giant Behemoth'', ''Film/TheGiantClaw'', ''Film/{{Gojira}}'', ''Film/{{Gorgo}}'', ''Film/ItCameFromBeneathTheSea'', ''Film/TheMonsterThatChallengedTheWorld'', ''Film/{{Reptilicus}}'', ''Film/{{Tarantula}}'' and ''Film/{{Them}}''.

The movie follows Professor Tom Nesbitt, the sole witness to the existence of a carnivorous dinosaur (Rhedosaurus) that was thawed due to a nuclear blast detonated in the Arctic. The monster makes its way down the coast of North America, wreaking destruction as it goes. The monster soon arrives at New York city, rising from the sea to prey on the hopeless civilians. Things are furthered complicated by a mysterious prehistoric disease carried by the beast; killing it would cause the disease to easily spread and kill the world's human population.

The movie was a huge hit, despite its relatively meagre budget, largely for its masterful stop-motion effects by RayHarryhausen, whose career this movie kick-started; indeed, it still looks pretty good to this day, for a '50s movie.

----
!!This film contains examples of:

* AdaptationalVillainy: In the short story that the movie is [[InNameOnly loosely]] inspired by, "The Fog Horn" by Creator/RayBradbury, the dinosaur is a much more sympathetic and tragic figure, coming to a lighthouse because it mistakes the horn for the cry of a member of its own species. Although it destroys the lighthouse in a rage when the horn is turned off, no one is killed, and it shows no interest in further destruction, returning to the ocean peacefully. The human characters respond to it with sympathy and respect, indeed never even considering killing it.
* AdventureRebuff: Tom Nesbitt asks paleontologist Thurgood Elson to fit out an expedition to search for a living breathing prehistoric monster. Dr. Elson finds the idea of a prehistoric monster living in modern times far-fetched and declines Tom's request. See IronicEcho below.
* AgentScully: Most of the characters in the movie scoff at the idea of sea monsters.
* AmusementPark: The climax of the film takes place at Coney Island, as the lights and sounds attract the beast. A crack sharpshooter (Lee Van Cleef) takes a ride on one of the rollercoasters to get close enough to shoot a highly-radioactive bullet into the monster. The monster's death-throes smash the heck out the various rides. The scene was later given an homage in an episode of the ''Film/{{Ghostbusters}}'' animated series.
* CanadaEh: See FunnyForeigner.
* TheCameo: A Rhedosaurus appeared in ''PlanetOfTheDinosaurs'' and in ''When Dinosaurs Ruled the Earth''.
** EarlyBirdCameo: When Tom is looking through pictures to identify the beast, one of the dinosaurs shown would eventually get a starring role in ''Gorgo''.
* DeathByAdaptation: The Beast itself. In the short story that the film was inspired by, it survives and goes back to the sea peacefully.
* DepletedPhlebotinumShells: The only way to safely kill the beast.
* ILoveNuclearPower: See FollowTheLeader below.
* IronicEcho: "If every account of anyone ever seeing a monster was laid end-to-end, they'd reach the moon".
* ImmuneToBullets: The Beast is not so much immune as dangerous to injure. A shell from one of the big guns opens a wound, but its blood carries a deadly disease.
* FollowTheLeader: This was the first movie where the atom bomb was responsible for the existence of the monster. It was followed by ''Film/{{Them}}'', ''Film/TheDeadlyMantis'', ''Film/EarthVsTheSpider'', and, most famously, ''Film/{{Gojira}}''.
* FunnyForeigner: Georges [=LeMay=], the humourous Quebecois fisherman. There's a Nova Scotian fisherman named Jacob Bowman who is much more toned-down and believable. Tom himself, implicitly Swiss, is written off as this by a few people.
* HeyItsThatGuy: [[Film/TheGoodTheBadAndTheUgly Angel Eyes]] can pick his teeth with a rocket-propelled grenade launcher.
* KillItWithFire: Defied. The giant dinosaur could be killed with fire, or with a lot of other things, but fire would carry its diseased particles all over the world and we'd all die anyway.
* TheObiWan: Dr. Elson.
* {{Omniglot}}: Tom is revealed to be one when he talks to Georges [=LeMay=] on the phone in French. Tom is played by Swiss actor Paul Humbschmid (credited in the movie as "Paul Christian"), and quite a few Swiss speak French.
* RayBradbury: The story was partially inspired by the short story "The Foghorn." Sort of.
* ScienceIsBad: Averted; the portrayal of science is handled with far more subtlety and ambivalence than in most of the monster movies that followed; science unleashes the monster, but it's also the only effective way of killing the monster without making things even worse.
* SealedEvilInACan: Awakened for you by nuclear power!
* SeaMonster: When nobody believes Tom about the creature, he's referred to various other legendary sea serpents.
* ServileSnarker: The nurse
----