The plain antvireo (Dysithamnus mentalis) is a passerine bird species in subfamily Thamnophilinae of family Thamnophilidae, the "typical antbirds".

[3] The plain antvireo was described by the Dutch zoologist Coenraad Jacob Temminck in 1823 and given the binomial name Myothera mentalis.

Adult males of the nominate subspecies D. m. mentalis have a dark gray forehead and crown and blackish ear coverts.

Their lower breast, flanks, and crissum are pale gray and the center of their belly yellow.

Their upperparts and wings are more olive and less gray than the male's and they lack the white interscapular patch.

[3] The plain antvireo feeds mostly on insects; its diet also includes other arthropods like spiders and occasionally Rapanea mistletoe berries.

It typically feeds from near the ground to about 4 or 5 m (13 or 16 ft) above it, occasionally higher and very rarely up to the forest subcanopy.

It forages rather sluggishly, gleaning from a perch, and taking most of its prey from foliage though often from vines and sometimes thin branches and dead leaves.

It is typically suspended from a branch fork in a shrub or small tree between about 0.6 and 2.5 m (2 and 8 ft) above the ground.

[3] Breeding pairs are quite territorial against conspecifics, and in the Atlantic Forest defend a patch of habitat that may be as large as about 7,000 m2 (8,400 sq yd), but sometimes is only half that size.

The plain antvireo's song is generally a "short...series starting with a few...evenly paced, countable notes at same pitch, notes then gradually becoming more abrupt and dropping in pitch, ending in accelerating roll".