Copepteryx is an extinct genus of flightless bird of the family Plotopteridae, endemic to Japan during the Oligocene living from 28.4 to 23 mya, meaning it existed for approximately 5.4 million years.

In 1979, Storrs L. Olson and Hasegawa Yoshikazu identified them as those of plotopterids, but their abundance and diversity complicated their identification as distinct species.

In the same publication was also described another, larger species of Copepterix, C. titan, collected in 1983 by Ikeuchi Hideo in Ainoshima, with the left femur KMNH VP 200,004 as holotype.

[4] In 2009, Okazaki Yoshihiko referred to the genus an additional furcula, discovered in the Late Eocene to Early Oligocene of the Kishima Formation on Hikoshima.

[5] In 2020, Ohashi Tomoyuki and Hasegawa Yoshikazu assigned to the genus an additional left coracoid from the Yamaga Formation.

Copepteryx was a large-sized diving plotopterid bird, roughly similar to the contemporaneous giant penguins from the South Pacific, such as Waimanu.

[3] It has recently been suggested that C. titan would in fact represent the remains of male C. hexeris, as sexual dimorphism is often important in modern genera of cormorants and darters.