Theotokos (/ˌθiəˈtɒkəs/; Greek: Θεοτόκος, transliterated Theotókos) is the Greek title of Mary, the mother of Jesus used especially in the Eastern Orthodox, Oriental Orthodox, and Eastern Catholic Churches. Its literal English translations include God-bearer and the one who gives birth to God. Less literal translations include Mother of God. Roman Catholics and Anglicans use the title Mother of God more often than Theotokos. The Council of Ephesus decreed in 431 that Mary is Theotokos because her son Jesus is one person who is both God and man, divine and human.

Theotokos is a compound of two Greek words, Θεός God and τόκος parturition, childbirth. Literally, this translates as God-bearer or the one who gives birth to God; historian Jaroslav Pelikan translated it more precisely as "the one who gives birth to the one who is God". However, since many English-speaking Orthodox find this literal translation awkward, in liturgical use, Theotokos is often left untranslated, or paraphrased as Mother of God. The latter title is the literal translation of a distinct title in Greek, Μήτηρ του Θεού (translit. Mētēr tou Theou). Mother of God also accurately translates the Greek words Θεομήτωρ (translit. Theomētor; also spelled Θεομήτηρ, translit. Theomētēr) and Μητρόθεος (translit. Mētrotheos), which are found in patristic and liturgical texts, e.g.