Archen is a small, bipedal creature with mixed reptilian and avian traits. Its large, red head is covered in discernible scales, and its neck has blue and red feathers. Its body is covered in untidy, sallow feathers, with blue, clawed wings that cannot be used for flight. It has short, thin legs, and a thin, twig-like tail that bears a diamond-shaped blue feather. It has wide white eyes with black pupils and no irises.

It is believed to be the ancestor of all bird Pokémon.