3Edmund Mortimer, 2nd Baron Mortimer (1251 – July 17, 1304) was the second son and eventual heir of Roger Mortimer, 1st Baron Wigmore. His mother was Maud de Braose. As a younger son, Edmund had been intended for clerical or monastic life, and had been sent to study at Oxford University. He was made Treasurer of York in 1265. But the sudden death of his elder brother, Ralph, in 1276, made him heir to the family estates.
He returned in 1282 as the new Baron Mortimer of Wigmore and immediately became involved in Welsh Marches politics. Together with his brother Roger Mortimer of Chirk, John Giffard, and Roger Lestrange, he devised a plan to trap Llywelyn the Last. Edmund sent a message to Llywelyn telling him he was coming to Llywelyn's aid and arranged to meet with him at Builth. But Edmund's brothers secretly forded the river behind Llywelyn's army and surprised the Welsh. In the resulting battle Llywelyn was killed and beheaded. Edmund then send his brother Roger Mortimer of Chirk to present Llywelyn's severed head to King Edward I of England.
In September 1285, he married Margaret de Fiennes, the daughter of William II de Fiennes and Blanche de Brienne (herself the granddaughter of John of Brienne by his third wife Berenguela of Leon). Their children were:
1. Isolde Mortimer, married Hugh I de Audley
2. Roger Mortimer, 1st Earl of March
3. Maude Mortimer, married Theobald II de Verdun
Edmund was knighted by King Edward at Winchester, and served in the king's Gascon and Scottish campaigns. He was mortally wounded in a skirmish near Builth, and died at Wigmore Castle.