Kongs are extraordinarily tall apes with unmistakable similarities to ordinary Gorillas. They can grow up to 25 feet tall, have black fur, brown eyes, and walk on their knuckles. Although mostly found walking on all four limbs, they are capable of rearing up on their feet, as seen when beating their chest. Like gorillas, the male of the species can grow a white patch of fur on its back, likely indicating dominance, as it does for silverback gorillas. They possess immense physical strength, presumably scaled up from their smaller counterparts, and are capable of jumping virtically, something that ordinary gorillas have not been seen doing.
Kongs appear to possess intelligence comparable to those of ordinary apes, although some of their movements suggest a superior intelligence, more comparable to humans. Kong was seen intelligently tossing Ann Darrow around from hand to hand (to foot) during its fight with the three V. Rexes. It also displayed surprisingly advanced fighting tactics during that battle. It later appeared to playfully scoff at Ann just before picking her up and placing her on his shoulder, apparently realizing that she needs him more than he needs her.
Kongs also appear to be very affectionate and playful. It seemed to enjoy playing with Ann, first on top of mountain when it knocked her over repeating, seeming to enjoy watching her fall down, then later in New York at the skate rink. They are also very protective, as it was over Ann, risking its own life multiple times to protect her after seemingly falling in love. Like a protective parent, Kong reacts immediately to her cries of terror, and aids her with no regard for the danger (even the fighter planes, which couldn’t have possibly ever seen before).
Despite their effective adaptations, the species was eventually wiped out by a combination of natural causes, and being hunted by the other creatures.
The Kong from the 1933 film by Merian C. Cooper had only one survivor after it's death, Kiko, officially the last of it's species (made even rarer by it's unique albino fur). Kiko was killed when Skull Island sank, rendering the species officially extinct.
Following the events of the 1976 film by Dino De Laurentiis, it was discovered that King Kong was not the only giant ape around, finding a female in Borneo. The two Kongs successfully mate, producing a child. Despite Kong's death, the female and her child were seen back on Kong Island, rendering the species not extinct in this version (but still highly endangered).