Lethrus (Lethrus) thracicus Král Hillert, new species, from Thrace, north-western Turkey is described. The new species is compared with the morphologically similar species L. (L.) apterus (Laxmann, 1770), L. (L.) ares Král, Rejsek Schneider, 2001 and L. (L.) schneideri Král Hillert, 2013. Relevant diagnostic male characters (shape of mandibles, ventral mandible processes, pronotum and parameres) are illustrated. The name Lethrus subaeneus Fairmaire, 1866 is considered a nomen nudum.
Keywords: Coleoptera, Scarabaeoidea, Geotrupidae, Lethrinae, Lethrus, taxonomy, new species, nomen nudum, Balkan Peninsula, Palaearctic region.