The Topknot Pigeon (Lopholaimus antarcticus) is a pigeon native to Australia. It is also known by the name of "Flock Pigeon".

The birds are big, with length varying from 40 to 46 centimetres (16 to 18.4 inches). It has a pale grey breast, dark grey wings and a slaty-black tail with one light grey band. The beak is red-brown. The pigeon also has a flattened, wide and sweptback crest of feathers that commences at the beak to the nape of the neck. The crest consists of grey feathers at the front and brown-red feathers at the back. The juveniles are plainer in appearance with a brown bill. The tail band is less defined in the immature.

The Topknot Pigeon is generally found in groups that can number in the hundreds. They are strong fliers and are often spotted over rainforests and valleys but are also are found around palm trees, figs, eucalyptus forests and woodlands. They are completely arboreal. The birds tend to feed on fruits in canopy and often rest on trees above the canopy. They also gain water from raindrops from trees. They are occasionally found in open country seeking food. Birds can often be found from Cape York in Queensland to the South Coast of New South Wales near the coast but have been seen as south as Tasmania and the Gippsland Lakes in Victoria, depending on food availability. The species were observed in enormous numbers in areas that had rainforest but unfortunately, numbers are declining because of the clearance of rainforests. Topknot pigeons are a protected species in Australia.

The birds are rarely heard but seem to produce soft, grumbling grunting noises. They commonly skirmish with each other and when skirmishing, they make short screech noises (akin to a pig).

Breeding occurs from July to January, when nests are usually built in rainforest trees high above the ground. The nests consist of long and loose twigs. One egg is laid that is large and slightly glossy.

Rush Creek, SE Queensland, Australia