Risso's dolphin ('Grampus griseus') is the only species of dolphin in the genus 'Grampus'. Some of the closest related species to these dolphins include: pilot whales ('Globicephala spp') and pygmy killer whales ('Feresa attenuata').

Infants are dorsally grey to brown and ventrally cream-colored, with a white anchor-shaped area between the pectorals and around the mouth. In older calves, the nonwhite areas darken to nearly black, and then lighten (except for the always dark dorsal fin). Linear scars mostly from social interaction eventually cover the bulk of the body; scarring is a common feature in toothed whales, but Risso's dolphin tend to be unusually heavily scarred. Older individuals appear mostly white. Most individuals have two to seven pairs of teeth, all in the lower jaw.

They are found worldwide in temperate and tropical waters, in the Indian, Pacific and Atlantic Oceans, also the Persian Gulf, continental shelf on steep banks, with water depths varying from 400–1,000 m (1,300–3,300 ft) and water temperatures at least 10 °C (50 °F) and preferably 15–20 °C (59–68 °F).

They feed almost exclusively on neritic and oceanic squid, mostly nocturnally. Predation does not appear significant. Mass strandings are infrequent. Analysis carried out on the stomach contents of stranded specimens in Scotland showed that the most important species preyed on in Scottish waters is the curled octopus.

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