| The name Morwen refers to more than one character, item or concept. For a list of other meanings, see Morwen (disambiguation).
Morwen Steelsheen (Third Age 2922 – ?), also called Morwen of Lossarnach, was the queen to King Thengel of Rohan, and mother to his heir Théoden.
Morwen was a woman of the Gondorian outland of Lossarnach. She was seventeen years younger than her husband, and thus was most likely born in T.A. 2922. Thengel wedded her late in his life (T.A. 2943), and they lived for a time in her homeland of Lossarnach, to the south and west of Minas Tirith. When his father Fengel died, Thengel inherited Kingship of Rohan, and travelled with Morwen back to his own land. Morwen bore five children in all, including Thengel's heir Théoden, and his sister Théodwyn, who would be the mother of Éomer and Éowyn. She was called Steelsheen because of her grace. Morwen appears to have died sometime before the War of the Ring, as she is not mentioned in The Lord of the Rings or Appendices in that period.