Elysia subornata is a species of small sea slug, a marine opisthobranch gastropod mollusk in the family Plakobranchidae.

It has broad parapodia (fleshy protrusions at the side) with thick white margins sometimes edged in brown or black.

The parapodia are covered in tiny papillae (fleshy protuberances) and the rhinophores (sensory organs on the head) are also papillose.

It has been proposed that Elysia subornata could be used as a biological control agent against an invasive strain of the alga Caulerpa taxifolia in the northwestern Mediterranean Sea.

It doesn't survive the cool temperature of winter Mediterranean waters, and would therefore need to be raised on a large scale to have any significant effect.