Phaeocystida, also known as Phaeocystina, is a group of cercozoans in the class Phaeodarea. It was first described by Ernst Haeckel in 1887 and treated traditionally as a suborder, but later was raised to order level until Cavalier-Smith's classification lowered it again to suborder level. It belongs to the order Eodarida, characterised by simpler silica skeletons or a lack thereof.