The southern cassowary also known as double-wattled cassowary, Australian cassowary or two-wattled cassowary, is a large flightless black bird. It is one of the three living species of cassowary, alongside the dwarf cassowary and the northern cassowary. It is a ratite and therefore related to the emus, ostriches, rheas and kiwis,
The southern cassowary has stiff, bristly black plumage, a blue face and neck, red on the cape and two red wattles measuring around 17.8 cm in length hanging down around its throat. A horn-like brown casque, measuring 13 to 17 cm high, sits atop the head. The bill can range from 10 to 19 cm. The three-toed feet are thick and powerful, equipped with a lethal dagger-like claw up to 12 cm on the inner toe. The plumage is sexual dimorphic, but the female is dominant and larger with a longer casque, larger bill and brighter-coloured bare parts. The juveniles have brown longitudinal striped plumage.
It is the largest member of the cassowary family and is tied as the second heaviest bird on earth, at a maximum size estimated at 85 kg and 190 cm tall. Normally, this species ranges from 127 to 170 cm in length. The height is normally 1.5 to 1.8 m; females average 59 kg, while males average 30 to 35 kg. The northern cassowary is about the same size on average and is perhaps very mildly less sexually dimorphic than the southern. Most adult birds will weigh between 17 and 70 kg. It is technically the largest Asian bird.