紫螺（学名：Janthina janthina），是异腹足目紫螺科紫螺属的一种。主要分布于印度尼西亚、韩国、中国大陆、**，常栖息在浅海沙底、浮游生活。

Janthina janthina, common name the violet sea-snail or common violet snail, is a species of holoplanktonic sea snail, a marine gastropod mollusk in the family Janthinidae, the violet snails or purple storm snails.