John IV of Constantinople (died 2 September 595), also known as John Nesteutes (, Ioannes the Faster), was patriarch of Constantinople (12 April 582 – 2 September 595). He was the first to assume the title Ecumenical Patriarch. He is regarded as a saint by the Eastern Orthodox Church which holds a feast on 2 September.
Life
John IV (surnamed Jejunator, sometimes also Cappadox) was born at Constantinople of artisan parents, and worked as a goldsmith. Under the Patriarch John Scholasticus (565–577) he was deacon at the Hagia Sophia church; then he became sakellarios (an official who acts as patriarchal vicar for monasteries). He was famous for his ascetical life and called "the Faster". Under Eutychius of Constantinople (552–565 and 577–582) he became an important person among the clergy of the city. At Eutychius's death he was made patriarch by the Emperor Tiberius II Constantine (574–582).
According to one account, a horse show was scheduled in the Hippodrome on eve of the Feast of Pentecost. Patriarch John IV found his flock's attendance unacceptable. Through the patriarch's fervent prayer, a terrible thunderstorm arose with rain and hailstones so that everyone dispersed in fear and came to realize the inappropriateness of such entertainment. In 587 or 588, he summoned the bishops of the East in the name of the "Ecumenical Patriarch" to examine certain charges against Gregory of Antioch, Patriarch of Antioch, (although Fortescue questions on what authority).