Isabella Mortimer, lady of Clun and Oswestry

Isabella Mortimer, Lady of Clun and Oswestry (born after 1247; died before 1 April 1292) was a noblewoman and a member of an important and powerful Welsh Marcher family. Although often overshadowed in modern historiography by her better-known parents, she is now known to have played an important part in her family's struggles against Llywelyn ap Gruffudd and to have helped to secure the frontline at Shropshire in the run-up to English conquest of Wales. She was the wife and widow of John III FitzAlan, baron of Clun and Oswestry and de jure earl of Arundel. After a lengthy widowhood, she married for a second time (to Robert, Knight de Hastang, b. Staffordshire to Sir Robert de Hastang & Joane de Curli) and largely disappeared from the records.