O Thanagor (O King) is a song first introduced during the Warcraft III: The Frozen Throne closing cinematic. The song became a recurring lyrical leitmotif in World of Warcraft: Wrath of the Lich King, appearing in several songs, including Arthas, My Son and Invincible. The song also appears as part of the medley in the World of Warcraft: Cataclysm login screen theme, The Shattering.