Gill-man

The Gill-man is an iconic monster of cinema, appearing as the main antagonist of the 1953 horror film Creature from the Black Lagoon and its two sequels. This "man-fish" creature is the last of a race of amphibious humanoids that existed back in the Devonian age and resided in a lagoon deep in the Amazonian rainforest.

Creature from the Black Lagoon
After having found the fossilized remains of another Gill-man, a marine biology institute funds an expedition to the Amazon in order to find more remains. Though the Gill-man reacts violently to the intrusion, he develops a soft spot for the team's only female member, Kay and repeatedly tries to abduct her, going as far as building a makeshift dam to prevent their boat from escaping. After having killed numerous members of the expedition, the creature takes Kay to his underwater lair, where he is tracked down by the remaining survivors and riddled with bullets. The creature tries to escape by swimming deep into the lagoon, but dies from his injuries.

Revenge of the Creature
A year after the events of the first film, the Gill-man is shown to have survived and is captured by different scientists. He is sent to the Ocean Harbor Oceanarium in Florida, and quickly becomes a huge tourist attraction. He is studied by an animal psychologist and his ichthyology student. The psychologist's attempts at communicating with the Gill-man are hampered by his attraction to his student. The Gill-man breaks free from his tank and escapes into the ocean. It is not long before he begins stalking the ichthyology student and kidnaps her at a boat party. The Gill-man is soon tracked down by police and again gets shot multiple times, forcing him to flee into the ocean. He tries to swim away and supposedly dies from his wounds.

The Creature Walks Among Us
After living for a short while in a Florida river, the creature is found again, and after a vicious struggle, is accidentally immolated. The Gill-man's injuries are so severe that his scales and gills fall off, forcing his captors to perform surgery on him to prevent suffocation. X-rays on the creature show he has begun developing a land animal's lung structure, so a tracheotomy is performed, opening an air passage to the lungs, transforming the Gill-man into an air-breathing, nearly human animal. Dressing him in a suit made of sail cloth, the creature is taken to a California estate where he is imprisoned within an electric fence. Though they initially try to integrate the creature into human society, one of its captors frames it for a murder, and the creature ultimately escapes into the ocean.

Biology
The Gill-man is fully amphibious, capable of breathing both in and out of the water. As shown in the first film, it is vulnerable to rotenone. It also possesses superhuman strength, which is flamboyantly displayed in the second and third films. It also possesses large, webbed hands with sharp claws on the tip of each finger. The Gill-man's scaly skin is extremely tough, which combined with a fast acting healing factor, allows it to survive wounds which would be fatal to humans, such as gunshots and full immolation. As shown in the third film, the creature has a dormant set of lungs, should its gills be irreparably damaged. The Gill-man is slightly photophobic, due to its murky water habitat. 35% of the Gill-man's blood is composed of white corpuscles lacking a nucleus.