Cancellaria cooperii, common name Cooper's nutmeg, is a species of medium-sized to large sea snail, a marine gastropod mollusk in the family Cancellariidae, the nutmeg snails.

[1] This species attains a size of around 95 mm.

This species is an ectoparasite that parasitizes the Pacific electric ray, Torpedo californica, and perhaps other benthic fishes.

[2] Cooper's nutmeg is uncommonly found, offshore, on sandy substrate.

This nutmeg snail occurs in the Eastern Pacific Ocean from Monterey, California, to San Benito Island, in central Baja California, Mexico.