Oneillornis is a genus of passerine birds in the family Thamnophilidae. The species are native to the Amazon rainforest of South America.

The genus contains two species:

These two species were at one time included in the genus Gymnopithys. They were moved to this newly erected genus based on the results of a molecular phylogenetic study published in 2014. The type species is the lunulated antbird.

These species are specialist ant-followers that depend on swarms of army ants to flush insects and other arthropods out of the leaf litter.