Finnian of Clonard – also Finian, Fionán or Fionnán in Irish; or Finianus and Finanus in its Latinised form (470–549) – was one of the early Irish monastic saints, who founded Clonard Abbey in modern-day County Meath. The Twelve Apostles of Ireland studied under him. Finnian of Clonard is considered one of the fathers of Irish monasticism.

Celtic Christianity is a form of Christianity that was common, or held to be common, across the Celtic-speaking world during the Early Middle Ages. Some writers have described a distinct Celtic Church uniting the Celtic peoples and distinguishing them from adherents of the Roman Church, while others classify Celtic Christianity as a set of distinctive practices occurring in those areas. Varying scholars reject the former notion, but note that there were certain traditions and practices present in both the Irish and British churches that were not seen in the wider Christian world.