Ostenia is a genus of flies in the family Dolichopodidae.

It contains only one species, Ostenia robusta, which is endemic to New Zealand.

The species was first described by Frederick Hutton in 1901, and the genus was named after Carl Robert Osten-Sacken.

In 2012 and 2013, O. robusta larvae were found feeding on pupae of Costelytra zealandica (grass grub), suggesting that O. robusta are predators of C. zealandia pupae.

This article related to members of the fly family Dolichopodidae is a stub.