Castniomera is a monotypic moth genus in the family Castniidae described by Constant Vincent Houlbert in 1918.

Its single species, Castniomera atymnius, commonly known as the giant butterfly-moth, was first described by Johan Wilhelm Dalman in 1824.

[1] It is known from Mexico through Central America to Venezuela.

The larvae feed on Musaceae species.

This article relating to moth family Castniidae is a stub.