The Plaintive Cuckoo (Cacomantis merulinus) is a species of bird belonging to the genus Cacomantis in the cuckoo family Cuculidae. It is native to Asia, from India and China to Indonesia.
In Singapore, it is an uncommon breeding resident.
It has a typical morph and a hepatic morph. The typical morph has a grey upper body, and orange lower body. The hepatic morph has rufous upperparts and pale underparts, both with dark bars. The juvenile looks like hepatic morph.
The confusion species in Singapore is the Rusty-breasted Cuckoo, which has a yellow eye-ring.