The Oriental and eastern Palaearctic planthopper genus Orthopagus Uhler, 1897 (Hemiptera, Fulgoromorpha, Dictyopharidae, Dictyopharinae, Orthopagini) is revised. Six species are included: O. bartletti Song, Malenovský & Deckert, sp. n. (described from India), O. exoletus (Melichar, 1903), comb. n., stat. rev. (material studied from India and Sri Lanka), O. hainanensis Song, Chen & Liang, sp. n. (described from China: Hainan island), O. lunulifer Uhler, 1897 (the type species of the genus; confirmed from Japan, China, Vietnam, Laos, India, and Nepal), O. philippinus Melichar, 1914 (Philippines), and O. splendens (Germar, 1830) (confirmed from China, Vietnam, Thailand, India, Malaysia, and Indonesia). Orthopagus helios Melichar, 1912 is newly synonymized with O. lunulifer. Lectotypes are designated for O. helios, O. helios var. diffusus Melichar, 1912, O. elegans Melichar, 1912, and O. philippinus. Dictyophara indiana Walker, 1851 is considered a nomen dubium. All species are redescribed, including habitus photographs and detailed illustrations of the male genitalia. Female genitalia are described for the genus for the first time. A key for identification of the species of Orthopagus and a distribution map are given.