Saint Constantine refers to one or several different religious figures from early British or Pictish history. These individuals, often described as kings, are associated with various regions including Cornwall, Wales, Scotland, and Ireland. While some traditions identify him as a monarch of Dumnonia who underwent conversion, others link him to the missionary work in Scotland or monastic life in Ireland. Because multiple figures share this name, their identities and specific historical details often overlap in regional traditions and hagiographies.