The sooty shearwater, or tītī, or muttonbird, is a medium-large shearwater in the seabird family Procellariidae. In New Zealand, it is also known by its Māori name tītī, and as muttonbird, like its relatives the wedge-tailed shearwater and the Australian short-tailed shearwater.

Shearwaters are medium-sized long-winged seabirds in the petrel family Procellariidae. They have a global marine distribution, but are most common in temperate and cold waters, and are pelagic outside the breeding season.