Brewer's blackbird (Euphagus cyanocephalus) is a medium-sized New World blackbird. It is named after the ornithologist Thomas Mayo Brewer.
Adult males have black plumage with an iridescent purple head and neck and glossy bluish-green highlights on the rest of the body. The feet and legs are black and the eye is bright yellow. The female is brownish-grey with slight hints of the male's iridescence. The female's eye is dark brown, while the male's is bright yellow. Overall, they resemble the eastern member of the same genus, the rusty blackbird; the Brewer's blackbird, however, has a shorter bill and the male's head is iridescent purple. This bird is often mistaken for the common grackle but has a shorter tail. The call is a sharp check which is also distinguishable.