Phagomyxids are a group of obligate endoparasitic protists belonging to the subphylum Endomyxa in Cercozoa. Taxonomically, they are united under a single family Phagomyxidae, order Phagomyxida, sister to the plasmodiophores.

Phagomyxids are mainly parasites of brown algae, but some can parasite oomycetes.

The group was created in 1993 by Cavalier-Smith, when it contained only the genus Phagomyxa. Since then, Maullinia, a genus previously in Plasmodiophoridae, has joined the phagomyxids.