Officer in the Theban Legion, 4th century; martyred in the neighbourhood of Köln. Often celebrated with Victor.
Feast day: 10 October.
An office for Gereon and companions is in NL-Uu 406 (basically the same office as D-X H 104, fols 314v-318v, for Victor).
The sequence Maiestati sacrosancti is in a.o. B-Br 15073 and NL-At 206 A 11.