Leucia is a genus of marine polychaete worms belonging to the family Polynoidae, the scaleworms.

Leucia contains 2 species, both found in the northern Atlantic Ocean.

This genus is distinguished from the closely related genus Harmothoe by having sixteen pairs of elytra, as opposed to fifteen.

[1] Body short, 41 to 50 segments, 16 pairs of elytra.

Antennae, palps, dorsal and ventral cirri papillated.