Leptoceratopsidae is an extinct family of neoceratopsian dinosaurs from Asia, North America and possibly Europe.

Leptoceratopsids resembled, and were closely related to, other neoceratopsians, such as the families Protoceratopsidae and Ceratopsidae, but they were more primitive and generally smaller.

Leptoceratopsidae was originally named by Franz Nopcsa von Felső-Szilvás in 1923 as a subfamily Leptoceratopsinae, and its type species is Leptoceratops gracilis.

[1] All previously published neoceratopsian phylogenetic analyses were incorporated into the analysis of Eric M. Morschhauser and colleagues in 2019, along with all previously published diagnostic species excluding the incomplete juvenile Archaeoceratops yujingziensis and the problematic genera Bainoceratops, Lamaceratops, Platyceratops and Gobiceratops that are very closely related to and potentially synonymous with Bagaceratops.

[2] Psittacosaurus sinensis Psittacosaurus mongoliensis Yinlong downsi Chaoyangsaurus youngi Hualianceratops wucaiwanensis Xuanhuaceratops niei Stenopelix valdensis Liaoceratops yanzigouensis Archaeoceratops oshimai Aquilops americanus Auroraceratops rugosus Graciliceratops mongoliensis Asiaceratops salsopaludalis Mosaiceratops azumai Yamaceratops dorngobiensis Helioceratops brachygnathus Leptoceratops gracilis Ischioceratops zhuchengensis Prenoceratops pieganensis Udanoceratops tchizhovi Zhuchengceratops inexpectus Koreaceratops hwaseongensis Montanoceratops cerorhynchus Cerasinops hodgskissi Gryphoceratops morrisoni Unescoceratops kopelhusae Bagaceratops rozhdestvenskyi Magnirostris dodsoni Protoceratops hellenikorhinus Protoceratops andrewsi Ajkaceratops kozmai Zuniceratops christopheri Turanoceratops tardabilis Diabloceratops eatoni Ceratopsidae Definitive leptoceratopsids lived in Asia and Western North America during the Late Cretaceous around 83-66 million years ago.