Nicholas I Mystikos or Nicholas I Mysticus was the Ecumenical Patriarch of Constantinople from March 901 to February 907 and from May 912 to his death in 925. His feast day in the Eastern Orthodox Church is 16 May.
Nicholas I Mystikos (modern representation)
May 16 (Eastern Orthodox liturgics)
May 15 - Eastern Orthodox Church calendar - May 17
St. Alexander of Jerusalem.
St. Abdias (Abidas or Obadiah) of Persia (Menologion of Basil II, 10th century).
Patriarch Nicholas Mystikos.
The martyrdom of Vitus, Modestus, and Crescentia.