Scavengers are animals that feed on dead and decaying organic matter. Often the term is used to describe the consumption of carrion, the bodies of animals that have died from causes other than predation or the bodies of animals that have been killed by other predators. However, the term is also used to describe animals that feed on rotting plant matter or refuse.

Vultures and burying beetles are examples of scavengers that feed on carrion, pink bud moth and stag beetle larvae are examples of scavengers that feed on rotting plant matter, and raccoons and squirrels are examples of scavengers that feed on refuse. Carrion-eating scavengers are called necrophages.

Scavengers play an important role in ecosystems by preventing the accumulation of decaying matter and helping to recycle nutrients. Detritivores and decomposers complete this process, by consuming the remains left by scavengers.

The ability of an animal to scavenge helps it overcome fluctuations in food availability. The process and rate at which dead plant and animal material is scavenged is affected by both biotic and abiotic factors, such as plant species, carcass size, habitat, temperature, moisture levels, and seasons.

Scavenger is an alteration of scavager, from Middle English skawager meaning "customs collector", from skawage meaning "customs", from Old North French escauwage meaning "inspection", from schauwer meaning "to inspect", of Germanic origin; akin to Old English scēawian and German schauen meaning "to look at", and modern English "show" (with semantic drift).

Animals that subsist entirely or mainly on decaying biomass (e.g. dead animals, dead plants) are called obligate scavengers, while those capable of obtaining food via other methods are termed facultative scavengers. Animals that rely specifically on carrion as a food source are called obligate necrophages. Animals that feed on particulate plant or animal matter (e.g. humus, marine snow) are typically categorized as detritivores rather than scavengers. The midge fly Propsilocerus akamusi, which feeds on detritus in the sediment of freshwater lakes, is an example of a detritivore.

Obligate scavenging of carrion (obligate necrophagy) is rare among vertebrates, due to the difficulty of finding enough carrion without expending too much energy. New World vultures such as the black vulture, and Old World vultures such as the griffon vulture, white-backed vulture and lappet-faced vulture, are examples of obligate carrion scavengers.

Most of the vertebrates that eat carrion are facultative scavengers, capable of obtaining food via predation or other methods, and eating carrion opportunistically. Many large carnivores that hunt regularly, such as hyenas and jackals, but also animals rarely thought of as scavengers, such as African lions, leopards, and wolves will scavenge if given the chance. They may also use their size and ferocity to intimidate the original hunters into abandoning their kills (the cheetah is a notable victim, rather than a perpetrator). Gulls, crows and magpies frequently scavenge roadkill.