Panagia (Greek: Παναγία, pronounced [panaˈʝia], fem. of panágios, pan- + hágios, the All-Holy, or the Most Holy; also transliterated Panaghia or Panayia), in Medieval and Modern Greek, is one of the titles of Mary, Mother of God, used especially in Orthodox Christianity and Eastern Catholicism.

Most Greek churches dedicated to the Virgin Mary are called Panagia; the standard western Christian designation of "St. Mary" is rarely used in the East, as Mary is considered the holiest of all created beings and therefore of the highest status and glory of all the saints.

Panagia is also the term for a particular type of icon of the Theotokos, wherein she is facing the viewer directly, usually depicted full length with her hands in the orans position, and with a medallion showing the image of Christ as a child in front of her chest. This medallion symbolically represents Jesus within the womb of the Virgin Mary at the moment of the Incarnation. This type of icon is also called the Platytéra (Greek: Πλατυτέρα, literally wider or more spacious): poetically, by containing the Creator of the Universe in her womb, Mary has become Platytera ton ouranon (Πλατυτέρα τῶν Ουρανῶν), "more spacious than the Heavens". This type is also sometimes called the Virgin of the Sign or Our Lady of the Sign, a reference to Isaiah 7:14:

Therefore the Lord himself shall give you a sign; Behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel.

Such an image is often placed on the inside of the apse which rises directly over the altar of Orthodox churches. In contrast with standard religious mosaics which usually have gold backgrounds, the Platytera is often depicted on a dark blue background, sometimes dotted with gold stars: a reference to the Heavens.
As with most Orthodox icons of Mary, the letters ΜΡ ΘΥ (short for ΜΗΤΗΡ ΘΕΟΥ, "Mother of God") are usually placed on the upper left and right of the halo of the Virgin Mary.

By extension of this last sense, a panagia is an engolpion with an icon of the Theotokos, worn by an Orthodox bishop. They can be very simple or extremely elaborate, depending on the personal taste of the particular bishop.

When an Orthodox bishop is vested for the Divine Liturgy or another service, he wears a panagia and a pectoral cross over his other vestments. The primate of an autocephalous church, when fully vested, wears a panagia, a pectoral cross, and an engolpion of Jesus. Bishops of all ranks when not vested will usually wear the panagia alone over their riassa (cassock); this is often the detail that, to the casual observer, distinguishes a bishop from a priest or a monk. The panagia is usually oval in shape and crowned with a depiction of an Eastern mitre. Sometimes, bishops will wear a panagia which is either square (see picture, right) or shaped like a Byzantine double-headed eagle; this latter is especially true of Greek bishops.

When the bishop is vested before the Divine Liturgy, the panagia is presented to him on a tray. He blesses it with both hands and the subdeacons bring it to him to kiss and place the panagia around his neck, while the protodeacon swings the censer and says the following prayer: