Flabellina affinis is a species of sea slug, an aeolid nudibranch, a marine gastropod mollusk in the family Flabellinidae.
The species can grow to a length of 50 mm. It feeds primarily on species of Eudendrium, a very common hydroid genus in the Mediterranean Sea.
Flabellina affinis is often confused with Paraflabellina ischitana, but can be distinguished as follows:
This species is found in depths to 50 m in European waters in the Atlantic Ocean from Portugal to Ghana and the Canaries and is widespread in the Mediterranean Sea.
