The black-capped antwren (Herpsilochmus atricapillus) is a species of bird in subfamily Thamnophilinae of family Thamnophilidae, the "typical antbirds".

[2] The black-capped antwren was described by the Austrian ornithologist August von Pelzeln in 1868 and given its current binomial name Herpsilochmus atricapillus.

[5][6][7] The black-capped antwren is found from Maranhão and Rio Grande do Norte in northeastern Brazil south to Mato Grosso, Mato Grosso do Sul and extreme western Paraná and São Paulo, and into southeastern Bolivia, the northwestern Argentinian provinces of Jujuy and Salta, and northern and eastern Paraguay.

In northeastern Brazil it favors caatinga woodland, semi-deciduous mata-de-cipó, and humid evergreen forest.

It forages singly, in pairs, and in family groups and frequently as a member of a mixed-species feeding flock.

It usually captures prey by gleaning from live foliage, vines, and branches, mostly by reaching or short lunges from a perch.

[5] Adult black-capped antwrens have been recorded feeding juveniles in Brazil during January and February, but nothing else is known about the species' breeding biology.