Patrick (c. 389- c. 461) was a famous Celtic missionary to Ireland. Patrick (or, more correctly, Patricius) was captured at the age of 16 by pirates and was sold into slavery to sheepherders in Northern Ireland.
Columba (c. 521-597) was a renowned Irish Celtic missionary. He was probably born in County Donegal. His father was a member of the reigning family in Ireland and his mother was descended from royalty.