Edmund Mortimer
Sir Edmund Mortimer (1376–1409), a younger son of the Earl of March and great-grandson of Edward III through Lionel of Antwerp, held a crown claim. He supported Henry Bolingbroke despite his elder brother Roger's stronger claim, and after Roger's death in 1398 protected his young nephew's interests.
Fighting for Henry IV against Owain Glyndŵr, he was captured at Bryn Glas in June 1402. When the king forbade his ransom and seized his estates, Mortimer turned rebel, marrying Glyndŵr's daughter Catrin that November and promising to restore Richard II or crown his nephew.
In 1405 he joined the Tripartite Indenture with Glyndŵr and Northumberland. He died in the siege of Harlech Castle in 1409.