Thranduil, son of Oropher, was an Elven king who ruled over the Woodland Realm in the Second and Third Ages. Though inherently cautious, he eventually committed his kingdom to fighting against Sauron in the War of the Ring. He was the father of the Elven prince of Mirkwood, Legolas, who was a member of the Fellowship of the Ring.
In The Hobbit, Thranduil is only referred to as the Elvenking. Thranduil's sword is the Elven sword that was used by Thranduil in The Hobbit: The Desolation of Smaug and The Hobbit: The Battle of the Five Armies. It first appears in The Hobbit: The Desolation of Smaug and Thranduil used this sword to execute the Orc soldier Narzug after an interrogation.