Ryan A. Allen writes: "Wrath of the Lich King is a culmination of six years of lore that Blizzard has crafted and released to fans. It began in 2002 with Warcraft 3 and its expansion The Frozen Throne.
The human prince Arthas and Night elf Illidan forged deals with evil and became the central antagonists for most of the entire Warcraft series. In 2004 Blizzard released World of Warcraft. While Arthas and Illidan did not make appearances in its release the repercussions of their actions was present in many of the environments players could run around in. Three years later Blizzard released the first expansion, The Burning Crusade, and gave groups of players a chance to bring down one of Warcraft's main baddies… Illidan (now a half-elf, half-demon hybrid of considerable powers)"