Ixobrychus is a genus of bitterns, a group of wading bird in the heron family Ardeidae. It has a single representative species in each of North America, South America, Eurasia, and Australasia. The tropical species are largely resident, but the two northern species are partially migratory, with many birds moving south to warmer areas in winter.

Herons are long-legged, long-necked, freshwater and coastal birds in the family Ardeidae, with 72 recognised species, some of which are referred to as egrets or bitterns rather than herons. Members of the genera Botaurus and Ixobrychus are referred to as bitterns, and, together with the zigzag heron, or zigzag bittern, in the monotypic genus Zebrilus, form a monophyletic group within the Ardeidae. Egrets do not form a biologically distinct group from herons, and tend to be named differently because they are mainly white or have decorative plumes in breeding plumage. Herons, by evolutionary adaptation, have long beaks.