Marginocephalia ("fringed heads") is a clade of ornithischian dinosaurs that includes the thick-skulled pachycephalosaurs, and mostly horned ceratopsians. They were all herbivores, walking on two or four legs, and are characterized by a bony ridge or frill at the back of the skull. The clade evolved in the Late Jurassic period, and became common in the Late Cretaceous.

They died out in the Cretaceous-Paleogene Extinction Event.