Littorina is a genus of small sea snails, marine gastropod molluscs in the family Littorinidae, the winkles or periwinkles.

[2] These small snails live in the tidal zone of rocky shores.

In Europe there are about nine species in this genus, one of which is the rough periwinkle, Littorina saxatilis (Olivi, 1792).

Another closely related (supposed) species Littorina tenebrosa (Montagu 1802) was thought to be distinct because of its different ecological requirements, but current studies have shown that it is not at all clear whether the two are indeed separate species or whether L. tenebrosa is perhaps merely an ecotype (an ecological form) of L.

In the Baltic they live within the influence of freshwater, and frequently become distorted in consequence.