Monstrilloida is an order of copepods with a cosmopolitan distribution in the world's oceans. The order contains a single family, Monstrillidae; the family Thaumatopsyllidae was formerly included in the order, but is now usually placed in the Cyclopoida. The taxonomy of the family is undergoing a period of revision, although some necessary changes are apparent; for instance, the genus Strilloma is now considered a taxonomic synonym of Monstrilla, the largest genus.