Gwenllian (or Gwenllïan) (Welsh, a combination of gwen "fair, blessed, white" and llian "flaxen") was the name of several ladies who lived in medieval Wales. The two best known have, for different reasons, become symbols of Welsh patriotism and/or independence. It is also the name of a song by prominent Welsh songwriter Meic Stevens and Anglesey rock band Calfari.
- Gwenllian ferch Gruffydd (1097–1136) Her patriotic revolt and subsequent death in battle at Kidwelly Castle contributed to the Great Revolt of 1136
- Gwenllian ferch Llywelyn (1282–1337) A daughter of Llywelyn ap Gruffudd, Ein Llyw Olaf, and sister to Catherine his eldest daughter. Owain Glyndŵr was later to adopt the (lions rampant version) arms of Llywelyn on the basis of direct descent via Catherine, Catherine being an heraldic hieress of Llywelyn.[1][2][3][4][5]