Overview
Arthur is a male given name possibly of Brythonic Celtic origin. Another theory is that the name is from Latin origin, derived from the Roman clan Artorius who lived in Roman Britain for centuries.
Its popularity derives from it being the name of the legendary hero King Arthur. It may derive from the Celtic Artos meaning “Bear”.
A common spelling variant used in many Slavic, Romance, and Germanic languages is Artur. In Spanish and Italian it is Arturo.
Etymology
The earliest attestation of the name Arthur is in the early 9th century Welsh-Latin text Historia Brittonum, where it refers to a circa 5th century Romano-British general who fought against the invading Irish and Picts, and who later gave rise to the famous King Arthur of medieval legend and literature. A possible earlier mention of the same man is to be found in the epic Welsh poem Y Gododdin by Aneirin, which some scholars assign to the late 6th century, though this is still a matter of debate and the poem only survives in a late 13th century manuscript entitled the Book of Aneirin. A 9th-century Breton landowner named Arthur witnessed several charters collected in the Cartulary of Redon.
The Irish borrowed the name by the late 6th century (either from an early Archaic Welsh or Cumbric form Artur), producing Old Irish Artúr (Latinized as Arturius by Adomnán in his Life of St. Columba, written circa 697–700), The earliest historically attested bearer of the name is a son or grandson of Áedán mac Gabráin (died 609).
From Wikipedia (CC BY-SA 4.0).