Morgause on BBC's MERLIN

Morgause made her American debut tonight on the Syfy Channel's airing of "The Sins of the Father," episode eight of season 2 of the BBC's Merlin. Morgause is a sorceress and half-sister to Morgana, ward of Uther Pendragon, though both are unrelated to Arthur in the series, contrary to tradition. In this episode, Morgause uses her powers in an attempt to manipulate the young Prince Arthur against his father, Uther.

According to the Merlin Wiki, Morgause returns in episode twelve of the series, "The Fires Of Idirsholas."