The palm cockatoo (Probosciger aterrimus), also known as the goliath cockatoo or great black cockatoo, is a large smoky-grey or black parrot of the cockatoo family native to New Guinea, Aru Islands, and Cape York Peninsula. It has a very large black beak and prominent red cheek patches.
The palm cockatoo is 55 to 60 cm in length and weighs 910–1,200 g. It may be the largest cockatoo species and largest parrot in Australia, although large races of yellow-tailed black cockatoos and sulphur-crested cockatoos broadly overlap in size. It is a distinctive bird with a large crest and has one of the largest bills of any parrot (only the hyacinth macaw's is larger). This powerful bill enables palm cockatoos not only to eat very hard nuts and seeds, but also enables males to break off thick sticks from live trees to use for a drumming display. The male has a larger beak than the female. The beak is unusual, as the lower and upper mandibles do not meet for much of its length, allowing the tongue to hold a nut against the top mandible while the lower mandible works to open it. The palm cockatoo also has a distinctive red cheek patch that changes colour when the bird is alarmed or excited.
The palm cockatoo has a large and complex vocal repertoire, including many whistles and even a "hello" call that sounds surprisingly human-like. Distinct dialects occur throughout the species' range.