Photios I (Greek: Φώτιος, Phōtios; c. 810 – c. 893) also spelled Photius or Fotios and known by the Eastern Orthodox churches as St. Photios the Great, was Patriarch of Constantinople from 858 to 867 and from 877 to 886. Photios is widely regarded as the most powerful and influential Patriarch of Constantinople since John Chrysostom, and as the most important intellectual of his time, "the leading light of the ninth-century renaissance". He was a central figure in both the conversion of the Slavs to Christianity and the estrangement of the Eastern Orthodox churches from the Catholic Church. Photios is recognized as a saint by the Eastern Orthodox churches.