黏孢子虫（Myxosporea）是黏体动物（Myxozoa，有人称黏体动物亚门与黏体动物门）的一个纲。下有近1100种生物，较为知名的如寄生虫脑粘体虫（Myxobolus cerebralis）与Alataspora solomoni、Ceratomyxa shasta等。

The Myxosporea are a class of microscopic parasites, belonging to the Myxozoa. They have a complex life cycle which comprises vegetative forms in two hosts, an aquatic invertebrate (generally an annelid) and an ectothermic vertebrate, usually a fish. Each host releases a different type of spore. The two forms of spore are so different that until recently they were treated as belonging to different classes within the Myxozoa.