The topknot pigeon (Lopholaimus antarcticus) is a pigeon native to eastern Australia.
The topknot pigeon is a large predominately slate-grey bird, 40–46 cm in length. The back, coverts and upper secondaries are a darker slate-grey with black quills. The primaries are black, the remaining body in a lighter slate-grey in colour. The chest and hind neck are notched, showing dark bases giving a streaked appearance. The tail is black crossed with a board grey band. The crest is grey from the cere to the forehead, and russet brown on the crown with black sides. The mandibles are red with a brown tip, the protuberances at the base of the mandibles are bluish-green. The tarsals and feet are purplish red. The sexes are similar in description. However, Males have larger crest and lack some of the streaking on the chest. Juveniles are like females but the chest is mottled not streaked, the crest is smaller, with the cere and forehead being light brown, the crown grey. Tarsals and feet are reddish brown. The iris is yellow-golden with a bright red outer band. In fledglings the iris is brown.