Philiopsis is a genus of often colorful, medium-sized sea slugs, marine opisthobranch gastropod mollusks.

These are not nudibranchs; instead they are headshield slugs, in the clade Cephalaspidea.

[1] (Original description) Animal: The head disk is large, oblong-oval to triangular in shape, and does not extend beyond the foot.

Behind the head disk, the body forms a convex, fleshy lobe that begins beneath the overlapping head disk and extends to or just past the posterior portion of the foot.

The mouth is proboscidiform, positioned between the cephalic disk and foot, and may have a pair of tentacles on either side.