The Tricolored Blackbird, Agelaius tricolor, is a passerine bird of the family Icteridae. Its range is limited to the coastal areas of the Pacific coast of North America, from Northern California in the U.S. (with occasional strays into Oregon), to upper Baja California in Mexico.

This highly social and gregarious bird forms the largest colonies of any North American landbird, with a single breeding colony often consisting of tens of thousands of birds.

The common name is taken from the male bird's distinctive white stripes on bottom of their red shoulder patches, or "epaulets", which are visible when the bird is flying or displaying.

Despite the similar names, this bird is not related to the Old World Common Blackbird, which is a thrush (Turdidae).

In 2006 the Tricolored Blackbird was classified as Endangered by BirdLife International. Like the extinct Passenger Pigeon, the colonial nature of the Tricolored Blackbird makes it particularly vulnerable to extinction. Native grasslands once used for nesting and feeding have been lost to urban and agricultural development. Birds adapting to nesting in agricultural fields have been disturbed by harvesting during the breeding season.

The species' call is a mite more nasal than that of the Red-Wing's. Note, a nasal kip and a sharp check. The male's song is a garbled on-ke-kaaangh.