Antoninus Liberalis (Greek: Ἀντωνῖνος Λιβεράλις) was an Ancient Greek grammarian who probably flourished between AD 100 and 300.

His only surviving work is the Metamorphoses (Μεταμορφώσεων Συναγωγή, Metamorphoseon Synagoge, literally "Collection of Transformations"), a collection of forty-one very briefly summarised tales about mythical metamorphoses effected by offended deities, unique in that they are couched in prose, not verse. The literary genre of myths of transformations of men and women, heroes and nymphs, into stars (see Catasterismi), plants and animals, or springs, rocks and mountains, were widespread and popular in the classical world. This work has more polished parallels in the better-known Metamorphoses of Ovid and in the Metamorphoses of Lucius Apuleius. Like them, its sources, where they can be traced, are Hellenistic works, such as Nicander's Heteroeumenaand Ornithogonia ascribed to Boios.^[1]