Moduin, Modoin, or Mautwin (Latin: Moduinus, Modoinus, c.770–840/3) was a Frankish churchman and Latin poet of the Carolingian Renaissance. He was a close friend of Theodulf of Orléans, a contemporary and courtier of the emperors Charlemagne and Louis the Pious, and a member of the . In signing his own poems he used the nom de plume Naso in reference to the cognomen of Ovid. From 815 (or earlier) until his death he was the Bishop of Autun.
Moduin's early career in the church was spent at Saint-Georges in Lyon. He is first recorded in the diocese of Autun in 815, but it is not certain when he was elected or consecrated. He supported Louis the Pious and Charles the Bald during the civil wars of the 830s. After the deposition of Agobard at the Synod of Thionville in 835, Moduin took over many of the responsibilities of the Archbishop of Lyon. It was during his administration of Lyon that Florus accused him of mistreating the clergy.
Moduin may also have been the abbot of Moutiers-Saint-Jean in the Diocese of Langres.
Moduin was a court poet and as such his two surviving verses are secular. He is notable for his praise of Charlemagne and he has been called his panegyrist. Moduin's poem to Theodulf and especially his Egloga were a major influence on the later Carolingian poet Ermoldus Nigellus. Even Moduin's more famous contemporary Alcuin of York, quotes Moduin in his En tuus Albinus.