The black drongo (Dicrurus macrocercus) is a small Asian passerine bird of the drongo family Dicruridae. It is a common resident breeder in much of tropical southern Asia from southwest Iran through Pakistan, India, Bangladesh and Sri Lanka east to southern China and Indonesia and accidental visitor of Japan. It is an all black bird with a distinctive forked tail and measures 28 cm (11 in) in length. It feeds on insects, and is common in open agricultural areas and light forest throughout its range, perching conspicuously on a bare perch or along power or telephone lines.

The species is known for its aggressive behaviour towards much larger birds, such as crows, never hesitating to dive-bomb any bird of prey that invades its territory. This behaviour earns it the informal name of king crow. Smaller birds often nest in the well-guarded vicinity of a nesting black drongo. Previously grouped along with the African fork-tailed drongo (Dicrurus adsimilis), the Asian forms are now treated as a separate species with several distinct populations.

The black drongo is listed as least concern by the International Union for Conservation of Nature (IUCN) on the IUCN Red List, due to its large range and relative commonness. It has been introduced to some Pacific islands, where it has thrived and become abundant to the point of threatening and causing the extinction of native and endemic bird species there.

This bird is glossy black with a wide fork to the tail. Adults usually have a small white spot at the base of the gape. The iris is dark brown (not crimson as in the similar ashy drongo). The sexes cannot be told apart in the field. Juveniles are brownish and may have some white barring or speckling towards the belly and vent, and can be mistaken for the white-bellied drongo. First-year birds have white tips to the feathers of the belly, while second-years have these white-tipped feathers restricted to the vent.

They are aggressive and fearless birds, and although only 28 cm (11 in) in length, they will attack much larger species that enter their nesting territory, including crows and birds of prey. This behaviour led to their former name of king crow. They fly with strong flaps of the wing and are capable of fast manoeuvres that enable them to capture flying insects. With short legs, they sit upright on thorny bushes, bare perches or electricity wires. They may also perch on grazing animals.

They are capable of producing a wide range of calls but a common call is a two note tee-hee call resembling that of the shikra (Accipiter badius).