The black-billed koel (Eudynamys melanorhynchus) is a species of cuckoo in the Cuculidae family. It is endemic to forest and woodland on the Indonesian islands of Sulawesi, Sula, Banggai, Togian and other smaller nearby islands. It has often been considered conspecific with E. scolopaceus, but they are increasingly treated as separate species. Unlike the black-billed koel, all other members of the common koel complex have a pale bill.