The Blue-billed Black-tyrant is distributed from Minas Gerais and Espírito Santo south to Uruguay and north-east Argentina. Southern populations migrate northwards during the austral winter. It is found in the borders of Atlantic Rain Forest and in gallery woodland. Usually associated with water.

The male (not shown here) is glossy black with a pale greyish-blue bill and a red iris.

The female, seen here in photos 1 to 3, is very different being brown above with a more rufous crown and a rufous rump. The wings are black with two whitish wing bars while underparts are whitish with heavy dark streaks.  The iris is pale red to orange.