The cinereous antshrike (Thamnomanes caesius) is an insectivorous bird in subfamily Thamnophilinae of family Thamnophilidae, the "typical antbirds".

It is found in Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname, and Venezuela.

[2] The cinereous antshrike was described by the Dutch zoologist Coenraad Jacob Temminck in 1820 and given the binomial name Muscicapa caesius.

Adult males of the nominate subspecies T. c. caesius are almost entirely dark gray; the inner edges of their secondaries and their underwing coverts are white.

The subspecies are found thus:[8] The cinereous antshrike inhabits the understorey to mid-storey of terra firme, várzea, and igapó evergreen forest.

It mostly forages singly, in pairs, and family groups and usually as the central member of a mixed-species feeding flock.

The cinereous antshrike's song is a "series, starting with some slow, sharply rising notes, then descending as a short rattle".

Vast areas of suitable habitat are protected except within the range of the nominate subspecies T. c. caesius.