A Great Blue Heron (Ardea herodias) was observed killing a California butterfly ray (Gymnura marmorata) with a morphological abnormality off coastal California. Even though this heron species has previously been reported actively hunting batoids, this observation is the first documenting of an attack by a bird (or any other predator) on a butterfly ray. The behavior observed in this event adds butterfly rays as potential prey items of A. herodias and provides further insights on both this bird's ecology as a nearshore predator and that of ray species like G. marmorata as important prey.