Morgan has two entries on "Behind the Name," the second being feminine (from Arthurian Legend). Morgana is currently listed as a feminine form of Morgan (1), but it should also be considered a Latinization of Morgan (2), since the character has appeared in numerous adaptations as Morgana le Fay.
Morgana is a name of ancient literary origin known to people as the wizard Morgana and is recounted in "The Life of Merlin" in year 1150. A character later of several poems in the Breton cycle, also the sister of King Arthur. It is able to be traced back to Celtic origin to the name Muirgen, variant of Mor "Sea".