Ilgamuth of the Twisted Lip was a Calormene Tarkaan. He was one of the many who fought in Prince Rabadash's army at the Battle of Anvard, in an attempt to conquer Archenland. He was killed during the battle by an Archenland lord named Darrin.
Nothing else is known about him. However, given his title and the reputation of Calormen, it can be assumed that he was a corrupted, manipulative and deceitful man.