The name 'John' masc. proper name, c.1160, from Gk. Ioannes, from Heb. Yohanan (in full y'hohanan) lit. "Jehovah has favored," from hanan "he was gracious."  As the name of John the Baptist and John the Evangelist, it is one of the most common Christian given names.
There are approximately 130 saints with this name, or a common variant. Listed in Orthodox Wiki we have:
- Apostle John
- St. John Chrysostom, Archbishop of Constantinople (November 13 and September 14 and January 30)
- St. John Climacus (March 30), author of "the Ladder" or "Climacus"
- St. John Scholasticus
- St. John of Damascus
- St. John of Kronstadt
- St. John of Rila
- St. John of Vilna
- St. John the Forerunner
- February 24 - First and Second discoveries of the head.
- May 25 - The Third finding of his head.
- June 24 - Nativity of St. John.
- July 23 - Synaxis of the Baptist, Gr. Σύναξις.
- August 29 - The Beheading, Gr. Απότομη Τιμ. Κεφαλής.
- September 23 - The Conception, Gr. Σύλληψις.
Not so common saints (not yet listed on OW):
- St. John (Beverley) of England (March 7)
- St. John the Chinese (June 11), see the Bio of St. Mitrof Tsi
- St. John De Montfort, no commemoration.
- OrthodoxWiki Note: God is Gracious"