Hypomecis roboraria, the great oak beauty, is a moth of the family Geometridae.

The subspecies isabellaria is found in western Central Asia east across Siberia and Mongolia to northern China.

The male has feather-shaped antennae, the female thread-shaped.

The forewings have three narrow, wavy, dark cross-bands that are clear at the front edge, often blurry further back.

The larva is naked, brown and gnarled and strongly resembles a dead oak twig.