Aldisa cooperi is a species of sea slug, a dorid nudibranch, a marine gastropod mollusc in the family Cadlinidae.

[3] This demersal nudibranch is found in cold to temperate waters, from the intertidal to subtidal zones (up to a depth of 20 m), along the Pacific coast of North America, from California to Alaska.

[4] Cooper's aldisa is a small dorid nudibranch, growing to a length of 25 mm.

Its mantle has a yellow to orange color, with some black spots spread over it.

It is usually found nestled in its food sponge Anthoarcuata graciae.