Olcán is the name of an early Irish saint of the Dál Riata, disciple of St Patrick, founder and bishop of the monastery in Armoy in northeast County Antrim, Northern Ireland.

Dál Riata or Dál Riada was a Gaelic kingdom that encompassed the western seaboard of Scotland and north-eastern Ireland, on each side of the North Channel. At its height in the 6th and 7th centuries, it covered what is now Argyll in Scotland and part of County Antrim in Northern Ireland. After a period of expansion, Dál Riata eventually became associated with the Gaelic Kingdom of Alba.