Lewyn Martell

"At the Trident, Dorne lost 10,000 men and two princes: my uncle in the Kingsguard, and Elia's gallant husband, Prince Rhaegar, who was too slow or too arrogant for Robert's warhammer."

- Oberyn Martell

Prince Lewyn Martell was a knight in the Kingsguard of King Aerys II Targaryen, who became known as "the Mad King".

Background
Prince Lewyn Martell was the uncle of Doran, Elia, and Oberyn Martell. A younger son, he joined the elite Kingsguard, forswearing any claim to land and title.

During Robert's Rebellion, at the climactic Battle of the Trident, Prince Lewyn accompanied fellow Kingsguard Ser Barristan Selmy and Crown Prince Rhaegar Targaryen to face the rebel army led by Robert Baratheon. Prince Lewyn perished in the battle, along with thousands of other Dornishmen.

Prince Rhaegar also died in the battle, brought down by Robert's warhammer after an epic duel. Ser Barristan, Lewyn's fellow Kingsguard, was very badly wounded but due to the quick actions of Robert's maester ultimately survived.

In the books
In the A Song of Ice and Fire novels, Lewyn Martell is remembered fondly by his family as a kind man who loved his extended family. The Kingsguard are forbidden to marry or even to love, and in the past several have been severely punished even for having sexual affairs. As per the customs of Dorne, however, Prince Lewyn continued to secretly keep a paramour. Ser Barristan and the other Kingsguard were aware of it but kept his secret, as he did not let it interfere with his duty.

At the Battle of the Trident, Prince Lewyn led the large Dornish contingent (10,000 men strong) which threatened to break Robert Baratheon's left flank. During the fighting he became badly wounded, however, and in the confusion Ser Lyn Corbray led a counter-charge by the rebels, in which he personally dueled and killed Lewyn Martell. Ser Lyn - vain, arrogant, and secretly a pedophile - would in later years boast about how he had personally defeated Prince Lewyn, though in reality Prince Lewyn was already very badly wounded (perhaps mortally so) and Corbray simply finished him off.