Completing our survey of British non-avian dinosaurs, we here review the ornithischians of Britain. Heterodontosaurids are present in the Lower Cretaceous Lulworth Formation of Dorset, and a few earlier possible records imply a long presence in the region of this clade. Britain's thyreophoran record is rich and includes the earliest well-represented taxon, Scelidosaurus, as well as Middle Jurassic stegosaurs and ankylosaurs including a reasonably good Cretaceous record of polacanthids and nodosaurids. Cretaceous stegosaurs are known only from fragmentary remains, but the proposal that stegosaurs were present as early as the Rhaetian is rejected. Among British iguanodontian ornithopods, the possible dryosaurid Callovosaurus is the oldest global record whereas the proposed synonymy of Cumnoria with Camptosaurus requires confirmation. Iguanodon has become a taxonomic dumping ground for assorted iguanodontians and is in need of revision: most of the British species referred to this genus are almost certainly not closely allied to the neotype species I. bernissartensis and require new generic names. Fragmentary remains suggest the early presence of hadrosaurids in Britain. The only British record of Marginocephalia, the Wessex Formation skull roof named Yaverlandia bitholus, appears not to belong to this clade but seems to be from a maniraptoran theropod.