Theotokos (Greek: Θεοτόκος) is a title of Mary, mother of Jesus, used especially in Eastern Christianity. The usual Latin translations are Dei Genitrix or Deipara (approximately "parent (fem.) of God"). Familiar English translations are "Mother of God" or "God-bearer" – but these both have different literal equivalents in Greek, Μήτηρ Θεοῦ and Θεοφόρος ("Who gave birth to one who was God", "Whose child was God", respectively).

The title has been in use since the 3rd century, in the Syriac tradition (as Classical Syriac: ܝܠܕܬ ܐܠܗܐ, romanized: Yoldath Aloho) in the Liturgy of Mari and Addai (3rd century) and the Liturgy of St James (4th century). The Council of Ephesus in AD 431 decreed that Mary is the Theotokos because Her Son Jesus is both God and man: one divine person from two natures (divine and human) intimately and hypostatically united.

The title of Mother of God (Greek: Μήτηρ (τοῦ) Θεοῦ) or Mother of Incarnate God; abbreviated ΜΡ ΘΥ (the first and last letter of each word in Greek), is most often used in English, largely due to the lack of a satisfactory equivalent of the Greek τόκος. For the same reason, the title is often left untranslated, as "Theotokos", in Orthodox liturgical usage of other languages.

Theotokos is also used as the term for an Eastern icon, or type of icon, of the Mother with Child (typically called a Madonna in western tradition), as in "the Theotokos of Vladimir" both for the original 12th-century icon and for icons that are copies or imitate its composition.