蛙壶菌（学名：Batrachochytrium dendrobatidis）是一种壶菌门真菌，可以引起两栖类的壶菌病。它们最初是于1998年发现，在其后的十年内，造成了大量两栖类的死亡，引发多个物种灭绝，是为全新世灭绝事件之一。被国际自然保护联盟物种存续委员会的入侵物种专家小组（ISSG）列入世界百大外来入侵种。

一些两栖类物种具有天生的免疫能力。就算一些患上壶菌病的物种，也能够生存下来，显示出演化性选择的痕迹或等位基因。不过另一个解释却指一些蛙壶菌的形态并非真正的病原体。

Batrachochytrium dendrobatidis, (bə-TRAY-koh-KIT-ri-um DEN-droh-bə-teye-dis) also known as Bd or the amphibian chytrid fungus, is a chytrid fungus that causes the disease chytridiomycosis in amphibians. In the decade after it was first discovered in 1998, the disease devastated amphibian populations around the world, in a global decline towards multiple extinctions, part of the Holocene extinction. A recently described second species, B. salamandrivorans, also cause chytridiomycosis and death in salamanders.