Conan Meriadoc is a legendary British Celtic leader credited with founding Brittany. Versions of his story circulated in both Brittany and Great Britain from at least the early 12th century, and supplanted earlier legends of Brittany's foundation. His story is known in two major versions, which appear in the Welsh text known as The Dream of Macsen Wledig, and in Geoffrey of Monmouth's Historia Regum Britanniae. Both texts associate him with Magnus Maximus, a Roman usurper against the Valentinianic dynasty who was widely regarded as having deprived Britain of its defences when he took its legions to claim the imperial throne. Conan's cousin or sister, Saint Elen, is said to have been Macsen Wledic's wife.

Brittany is a peninsula, historical country and cultural area in the north-west of modern France, covering the western part of what was known as Armorica during the period of Roman occupation. It became an independent kingdom and then a duchy before being united with the Kingdom of France in 1532 as a province governed as a separate nation under the crown.