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.

The family Procellariidae is a group of seabirds that comprises the fulmarine petrels, the gadfly petrels, the diving petrels, the prions, and the shearwaters. This family is part of the bird order Procellariiformes, which also includes the albatrosses and the storm petrels.