Creature from the Black Lagoon

Creature From the Black Lagoon is a Universal Horror film from 1954. Tells the story of "the Devonian man," an amphibious creature that has existed since the age of dinosaurs in such a perfect condition that it has not had to evolve. An expedition is organized to go into heart of the Brazilian Jungle where "Evolution has stopped" to try and find a living specimen. Naturally, Gill Man is highly territorial and lonely, killing and drowning anyone he can get his claws on. He's also highly intelligent; once the Ignored Expert convinces the crew to leave while they can, Gill Man barricades the exit to the lagoon by toppling a tree so he can finish them off.

Notable for its beautiful underwater shots (the 3-D version of the movie is breathtaking), artful full-body submersible costuming for Gill Man, location filming (in Wakulla Springs ,Florida rather than Brazil, but still good) and the quick, graceful swimming of Gill Man--Ricou Browning, who played him underwater, was an Olympic Swimmer. Of course, above water he's a slow, waddling horror, but has titanic strength and jaguar-sharp claws to make up for it. Also notable for being very suspenseful and restrained compared to other B Movies, only showing Gill Man's hand and silhouette at first, and teasing the audience with having him stalk the female lead underwater almost shyly.

Had two lackluster sequels, Revenge of the Creature (1955), which was featured on Mystery Science Theater 3000, and The Creature Walks Among Us (1956). A remake is currently in Development Hell.

There's also a musical based on it.

Not to be confused with the anime Black Lagoon.

Tropes:

 * Three D Movie: Originally released as one.
 * The Amazon
 * Big No: Kay lets out one when Gill Man tries to capture her.
 * Boisterous Bruiser: Captain Lucas.
 * Cigar Chomper: Captain Lucas.
 * Distinguished Gentlemans Pipe: Dr. Thompson prefers to smoke from a pipe.
 * Egomaniac Hunter: Mark.
 * Evolutionary Levels
 * Fish People: The Creature may be the most famous example.
 * Fountain of Expies: Lots of fish men in other media took notes from Gill Man.
 * Get a Hold of Yourself Man: Lucas gives a slap to the sobbing Zee after Gill Man drags his brother Chico underwater.
 * Green Aesop: A rather more subtle one that you wouldn't expect from a 50s monster movie. The first film's message appears to be about conserving by not interfering with it, exemplified by the conflict between the two male leads. One insists on killing the Creature and bringing its body back to America, while the lead scientist wants to let the Creature live in peace and study it. There's a scene where the heroine casually throws a cigarette in the water, and the creature looking up at it floating on the surface. The Creature only attacks because it feels provoked by these strangers messing with him and his territory, and the man trying to kill him only makes things worse, so there's the added aesop of "violence begets violence." This was an intentionally done by one of the scriptwriters as a not so clear way teaching the audience to not be cruel to those who are different.
 * Harpoon Gun: Mark brought one with him.
 * It Can Think: Gill Man shows off his intelligence when it blocks path out of the lagoon and sinks one of ship Rita's boats.
 * Leitmotif: Gill Man's theme tune is a three-note key "Dun-dun-DAAA!”
 * Man On Fire: Dr. Thompson sets Gill Man on fire with a well placed lantern strike when it attacks him.
 * Mars Needs Women: Gill Man, being the last of his kind, must have wanted a “mate.”
 * Subject to the same Unfortunate Implications as King Kong and other films, with a "they're coming to take our white women" subtext.
 * Monster Misogyny: Subverted; Gill Man mostly slaughters and kills men, albeit he kidnaps two women and befriends another throughout his three movies.
 * Novelization: By an unknown author under the pseudonym "Carl Dreadstone" which barely resembles the film, renaming almost all of the characters, killing off nearly everyone who survived in the actual movie, and depicting the titular monster as a Godzilla-sized aquatic hermaphroditic pig-lizard.
 * People in Rubber Suits: Almost the architype
 * Red Shirt: The two Brazilian diggers in the first movie, slashed to horrified death
 * Scenery Porn: The underwater shots.
 * Screaming Woman
 * The Smurfette Principle: Kay.
 * Stuff Blowing Up: The opening narration plays while explosions simulating Earth's creation happen.
 * Touch of the Monster: An alternative poster shows Gill Man holding the beauty this way
 * The Watson: Captain Lucas needs the basic concept of geology/paleontology explained to him. The screenwriter must not have thought the audience would understand why, in the simplest terms, there's any reason to dredge up old rocks.
 * What Measure Is a Non Unique

The sequels have:

 * Ignored Expert: At various points, saner people point out that putting him in a petting zoo and trying to teach him to be human are not safe bets.