Alan (Alain, Allan, Alun, Alyn, Allen, Ailean, Ailín) is a male given name. Its origin is uncertain. It may ultimately derived from the Alanus "of the tribe of the Alans"( http://en.wikipedia.org/wiki/Alans ), or from Aelius, a given name ultimately from Helios "Sun", or from a Breton word for "rock".
It was introduced to England by Bretons before and after the Norman Conquest of England, having been popularized in their province as the misspelled name of Allorus (feast date 27 Dec.), bishop of Quimper. Having a similar name and feast date only a month apart, Allorus was thus conflated with Saint Alan (feast date 25 Nov.) of Lavaur Cathedral in Gascony near Toulose, whose name was a Vulgar Latin spelling of Aelianus, being recorded variously Alen or Elan.
Aelianus is a developed form of Aelius, itself a Roman borrowing of the Greek Helios. There is a Church of Saint Elian in Syria. The name is interpreted as meaning either "little rock" or "handsome" in Breton, and "harmony" in some Celtic languages.