Ephrem the Syrian (Classical Syriac: ܡܪܝ ܐܦܪܝܡ ܣܘܪܝܝܐ‎, romanized: Mār ʾAp̄rêm Sūryāyā, Classical Syriac pronunciation: [mɑr ʔafˈrem surˈjɑjɑ]; Koinē Greek: Ἐφραίμ ὁ Σῦρος, romanized: Efrém o Sýros; Latin: Ephraem Syrus; c. 306 – 373), also known as Saint Ephrem, Ephrem of Edessa or Ephrem of Nisibis, was a prominent Christian theologian and writer, who is revered as one of the most notable hymnographers of the Eastern Christianity. He was born in Nisibis, served as a deacon and later lived in Edessa.

Ephrem is venerated as a saint by all traditional Churches. He is especially revered in Syriac Christianity, most notaby in the Syriac Orthodox Church, and also counted as a Venerable Father (i.e., a sainted Monk) in the Eastern Orthodox Church. His feast day is celebrated on 28 January and on the Saturday of the Venerable Fathers. He was declared a Doctor of the Church in the Roman Catholic Church in 1920.

Ephrem wrote a wide variety of hymns, poems, and sermons in verse, as well as prose exegesis. These were works of practical theology for the edification of the Church in troubled times. So popular were his works, that, for centuries after his death, Christian authors wrote hundreds of pseudepigraphal works in his name. He has been called the most significant of all of the fathers of the Syriac-speaking church tradition.