Maximus V (Greek: Μάξιμος Ε΄; 26 October 1897 – 1 January 1972) was an Orthodox Christian bishop. He was Ecumenical Patriarch of Constantinople from 1946 until 1948.
He was born Maximos Vaportzis in northern Turkey, at Sinop in Kastamonu Vilayet, on the Black Sea coast. He was first educated, under the protection of metropolitan bishop Germanos of Amaseia, at the Theological School of Halki, Istanbul.
In 1918 he was ordained a deacon. With this appointment he also became teacher at the city school of Theira. He served as arch-deacon under Metropolitans Gregorios of Chalcedon and Joachim of Ephesus. In 1920 he became the archdeacon to the Ecumenical Patriarchate itself.
In 1946 he became Patriarch of Constantinople. He was known for his 'leftist' opinions and ties with the Moscow Patriarchate. He resigned in 1948, officially because of poor health; unofficially because western powers did not approve his ties with the Soviet-controlled Patriarch of Moscow. He was succeeded by the archbishop of America, Athenagoras, and was given the title of Ephesus.
He died in Switzerland on January 1, 1972.