Andrew of Constantinople (Andrew the Fool-for-Christ, Andrew, the Fool or Andrew, Fool-for-Christ-sake, Greek: ̓Ανδρέας ὁ Σαλός), (died in 936) is considered a saint by the Eastern Orthodox Church, and is revered as a Fool for Christ.
Andrew, a Slav by birth, was a slave of Theognostus, who was serving as a bodyguard in Constantinople. Later, he decided to become a Fool for Christ, living out his goal with humility and patience.
According to certain sources, Andrew had a vision of Most Holy Theotokos in the Blachernae church of Constantinople, while the city was surrounded by enemy troops (by some sources, Muslim Arabs).
Andrew and his disciple Epiphanus testified that they saw the Holy Virgin surrounded by many angels and Saints, praying and extending Her homophor (protection) over the faithful. After this vision, Constantinople was saved when its attackers retreated. That vision and the avoidance of Constantinople's destruction that was attributed to it inspired the creation of one of the most famous Eastern Orthodox holidays: the feast of the Protection of Our Most Holy Lady Theotokos and Ever-Virgin Mary.
Andrew died in 936. His memory is commemorated by Eastern Orthodox communities on October 15 (Oct. 2 old calendar). The earliest manuscript of his Greek vita is a quire in Munich in a 10th century uncial script. The work was also translated into Georgian and Slavonic.