Megaloceros (from Greek: μεγαλος megalos + κερας keras, literally "Great Horn"; see also Lister (1987)) is an extinct genus of deer whose members lived throughout Eurasia from the Pleistocene to the early Holocene.

[1][2][3] Megaloceros has been suggested to be closely related to other genera of "giant deer", like the East Asian genus Sinomegaceros, and the European Praemegaceros.

Megaloceros giganteus was originally described in 1799 as Alce gigantea by Johann Friedrich Blumenbach based on specimens found in Ireland.

[7] The type and only species named in the description being Megaloceros antiquorum, based on Irish remains now considered to belong to M. giganteus, making the former a junior synonym.

[8] In 1828 Brookes published an expanded list in the form of a catalogue for an upcoming auction, which included the Latin phrase "Cornibus deciduis palmatis" ("palmate deciduous horns") as a description of the remains.

[8] Adrian Lister in 1987 judged that "the phase "Cornibus deciduis palmatis" constitutes a definition sufficient under the [International Code of Zoological Nomenclature] (article 12) to validate Megalocerus.