Black-crowned Night Herons have a distinctive dark bluish grey to black back and crown, and pale grey wings. Its underparts are greyish white-buff and its legs pale yellow.

This species is gregarious and largely nocturnal, and during the day it rests in trees or bushes.

This species' scientific designation Nycticorax nycticorax means ‘night raven’ and like its common name, refers to its nocturnal habits, but also to its harsh crow-like call.