Martyr
Martyr Gereon of Cologne (Orthodox veneration unconfirmed)
†ок. 304
Gereon of Cologne — according to tradition, an officer of the legendary Theban Legion, executed with his fellow soldiers near Cologne under Emperor Diocletian (c. 304); venerated as patron of Cologne in the Catholic tradition, but his veneration in the Orthodox Church is not confirmed by any source.
According to Western tradition, Gereon was an officer of the legendary Theban Legion — a Roman military unit said to have been recruited from Christians of Egyptian Thebes, nearly wiped out for refusing to offer sacrifice to pagan gods. Gereon and a group of his companions were executed near Cologne under Emperor Diocletian, around 304. He is venerated as patron of the city of Cologne, where a basilica, St. Gereon's, was built over his burial site and decorated with a fresco c. 1240-1250 (the source of this entry's image) depicting the martyr in military dress.
IMPORTANT CAVEAT: neither azbyka.ru nor days.pravoslavie.ru carries a dedicated article on Gereon; pravenc.ru explicitly classifies him under "Catholic Saints," without listing an Orthodox calendar date. Unlike several other Western martyrs in this database (e.g., Gervasius and Protasius of Milan), no Orthodox source confirming liturgical veneration of Gereon was found — this entry is marked as lacking confirmed Orthodox veneration.