The Papuan harrier (Circus spilothorax) is a bird of prey native to New Guinea which belongs to the harrier genus Circus. It is commonly classified as a subspecies of the eastern marsh harrier (Circus spilonotus) of eastern Asia. However it may be a separate species or alternatively a subspecies of the swamp harrier (Circus approximans) of Australasia. In the central highlands and the Sepik valley there is a dark morph; males of this form are mostly blackish with a grey tail and the females are mostly dark brown.