The head and neck are bald, with the skin color varying, including yellow, orange, blue, purple, and red.

The bird was also assigned to the genus Gyparchus by Constantin Wilhelm Lambert Gloger in 1841, but this classification is not used in modern literature since Sarcoramphus has priority as the earlier name.

[9] An alternative theory reports that the name is derived from Mayan legends, in which the bird was a king who served as a messenger between humans and the gods.

[16] The South American Classification Committee has removed the New World vultures from Ciconiiformes and instead placed them in Incertae sedis, but notes that a move to Falconiformes or Cathartiformes is possible.

The Kern vulture (Sarcoramphus kernense), lived in southwestern North America during the mid-Pliocene (Piacenzian), some 3.5–2.5 million years ago).

As per Loye H. Miller's original description, "[c]ompared with [S. papa] the type conforms in general form and curvature except for its greater size and robustness.

"[18] The large span in time between the existence of the two species suggests that the Kern vulture might be distinct, but as the fossil is somewhat damaged and rather non-diagnostic, even assignment to this genus is not completely certain.

[20] A supposed king vulture relative from Quaternary cave deposits in Cuba turned out to be bones of the eagle-sized hawk Buteogallus borrasi (formerly in Titanohierax).

The fossil record, though scant, supports the theory that the ancestral king vultures and South American condors separated at least some 5 mya.

[23] However, no other naturalists recorded the painted vulture in Florida and sixty years after the sighting, its validity began to be questioned, leading to what John Cassin described as the most inviting problem in North American ornithology.

[23] Harper and several other researchers have attempted to prove the former existence of the king vulture, or a close relative, in Florida at this late date, suggesting that the population was in the process of extinction and finally disappeared during a cold spell.

[28] In stark contrast, the wing coverts, flight feathers, and tail are dark grey to black, as is the prominent thick neck ruff.

[29] On the head, the skin is wrinkled and folded, and there is a highly noticeable irregular golden crest attached to the cere above its orange and black bill;[3] this caruncle does not fully form until the bird's fourth year.

[3] The juvenile vulture has a dark bill and eyes, and a downy, gray neck that soon begins to turn the orange of an adult.

[28] Jack Eitniear of the Center for the Study of Tropical Birds in San Antonio, Texas reviewed the plumage of birds in captivity of various ages and found that ventral feathers were the first to begin turning white from two years of age onwards, followed by wing feathers, until the full adult plumage was achieved.

[35] The king vulture inhabits an estimated 14 million square kilometres (5,400,000 sq mi) between southern Mexico and northern Argentina.

[3] Pleistocene remains have been recovered from Buenos Aires Province in central Argentina, over 700 km (450 miles) south of its current range, giving rise to speculation on the habitat there at the time which had not been thought to be suitable.

[28] Birds have been observed engaging in tandem flight on two occasions in Venezuela by naturalist Marsha Schlee, who has proposed it could be a part of courtship behaviour.

[27] It is non-migratory and, unlike the turkey, lesser yellow-headed and American black vulture, it generally lives alone or in small family groups.

[48] The reproductive behaviour of the king vulture in the wild is poorly known, and much knowledge has been gained from observing birds in captivity,[49] particularly at the Paris Menagerie.

[48] A king vulture mates for life and generally lays a single unmarked white egg in its nest in a hollow in a tree.

[50] The king vulture eats anything from cattle carcasses down to corpses of monkeys and other arboreal mammals to beached fish and dead lizards.

[52] In densely forested areas, mammals likely to be included are many of the abundant sloths (Choloepus/Bradypus) whose combined ranges coincide largely with that of this vulture, but elsewhere it has adapted well to domestic livestock.

[52] Principally a carrion eater, there are isolated reports of it killing and eating injured animals, newborn calves, and small lizards.

[54] The king vulture primarily eats carrion found in the forest, though it is known to venture onto nearby savannas in search of food.

[48] The king vulture has also been recorded eating fallen fruit of the moriche palm when carrion is scarce in Bolívar state, Venezuela.

[56] This bird is a species of least concern to the IUCN,[1] with an estimated range of 14 million square kilometres (5,400,000 sq mi) and between 10,000 and 100,000 wild individuals.

An ocellated turkey (Meleagris ocellata) was also considered to be the bird depicted, but the hooked bill and wattle point to the raptor.