Diclonius (meaning "double sprout") is a genus of dinosaur from the Late Cretaceous.

Its fossils were found in the Judith River Formation of Montana, northern US.

[1] The type species, Diclonius pentagonus, was named by Edward Drinker Cope in 1876, based on a single tooth specimen (AMNH 3972).

Other formally undescribed species include D. calamarius and D. perangulatus.

Although Cope referred several other batches of teeth to the genus, under several species, the name is (for some people) considered a nomen dubium.