The Green-billed Coucal, Centropus chlororhynchus, is a member of the cuckoo order of birds, the Cuculiformes, which also includes the roadrunners, the anis, and the Hoatzin.

It is endemic to Sri Lanka. The Green-billed Coucal is a rare and shy species of the tall rainforests of southwest Sri Lanka. It nests in a bush, and the typical clutch is 2-3 eggs.

This is a large species at 43 cm. Its head and body are purple-black, the wings are maroon above and black below, and the long tail is dark green. The bill is a distinctive light green. Sexes are similar, but juveniles are duller and streaked.

The Green-billed Coucal takes a wide range of insects, caterpillars and small vertebrates, but snails are a favourite. It occasionally eats other food items.

This species is somewhat smaller and less contrasted than the widespread Greater Coucal. Despite its size and distinctive call, this is a difficult species to see because of the dense habitat in which it lives and its retiring nature.

This coucal has a small and declining population as a result of the forest destruction.