The great cormorant was formally described in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae under the binomial name Pelecanus carbo.

[3] The great cormorant is now one of 12 species placed in the genus Phalacrocorax that was introduced in 1760 by the French zoologist Mathurin Jacques Brisson.

[4] The genus name is Latinised Ancient Greek, from φαλακρός (phalakros, "bald") and κόραξ (korax, "raven"); the specific epithet carbo is Latin for "charcoal".

[4] Two additional species are very closely related, with genetic evidence suggesting they may be embedded within P. carbo;[6] they are shown in the list below for completeness.

In bulk if not in linear dimensions, the blue-eyed shag species complex of the Southern Oceans are scarcely smaller at average.

Adults have white filoplume patches on the thighs and on the head and upper neck in the breeding season.

In European waters it can be distinguished from the common shag by its larger size, heavier build, thicker bill, lack of a crest and plumage without any green tinge.

[citation needed] The type subspecies, P. c. carbo, is found mainly in Atlantic waters and nearby inland areas: on western European coasts and east across the Palearctic to Siberia and to North Africa, the Faroe Islands, Iceland and Greenland; and on the eastern seaboard of North America.

It builds its nest, which is made from sticks, in trees, on the ledges of cliffs, and on the ground on rocky islands that are free of predators.

[20] The average weight of fish taken by great cormorants increases with decreasing air and water temperature.

[21] In some freshwater systems, the losses of fish due to overwintering great cormorants were estimated to be up to 80 kg per ha each year (e.g. Vltava River, Czech Republic).

[20] Studies suggest that their hearing has evolved for underwater usage, possibly aiding their detection of fish.

In this practice, fishermen tie a line around the throats of cormorants, tight enough to prevent swallowing the larger fish they catch, and deploy them from small boats.

An old legend states that people who die far out at sea, whose bodies are never recovered, spend eternity on the island Utrøst – which can only occasionally be found by mortals.