Giant petrels form a genus, Macronectes, from the family Procellariidae, which consists of two living and one extinct species. They are the largest birds in this family. The living species are restricted to the Southern Hemisphere, and though their distributions overlap significantly, with both species breeding on the Prince Edward Islands, Crozet Islands, Kerguelen Islands, Macquarie Island, and South Georgia, many southern giant petrels nest farther south, with colonies as far south as Antarctica. Giant petrels are extremely aggressive predators and scavengers, inspiring another common name, the stinker. South Sea whalers used to call them gluttons. They are the only member of their family that is capable of walking on land.

Procellariiformes is an order of seabirds that comprises four families: the albatrosses, the petrels and shearwaters, and two families of storm petrels. Formerly called Tubinares and still called tubenoses in English, procellariiforms are often referred to collectively as the petrels, a term that has been applied to all members of the order, or more commonly all the families except the albatrosses. They are almost exclusively pelagic, and have a cosmopolitan distribution across the world's oceans, with the highest diversity being around New Zealand.