The black-footed ferret (Mustela nigripes), also known as the American polecat or prairie dog hunter, is a species of mustelid native to central North America.

The black-footed ferret is roughly the size of a mink and is similar in appearance to the European polecat and the Asian steppe polecat. It is largely nocturnal and solitary, except when breeding or raising litters. Up to 90% of its diet is composed of prairie dogs.

The species declined throughout the 20th century, primarily as a result of decreases in prairie dog populations and sylvatic plague. It was declared extinct in 1979, but a residual wild population was discovered in Meeteetse, Wyoming in 1981. A captive-breeding program launched by the United States Fish and Wildlife Service resulted in its reintroduction into eight western US states, Canada, and Mexico from 1991 to 2009. As of 2015, over 200 mature individuals are in the wild across 18 populations, with four self-sustaining populations in South Dakota, Arizona, and Wyoming. It was first listed as "endangered" in 1982, then listed as "extinct in the wild" in 1996 before being upgraded back to "endangered" in the IUCN Red List in 2008. In February 2021, the first successful clone of a black-footed ferret, a female named Elizabeth Ann, was introduced to the public.