Arthas Menethil (also known as "The Lich King") is a unlockable character in Guitar Hero: Warriors of Rock and is unlocked by reaching Rank 71 in Quickplay+ by collecting at least 1600 stars.

He is originally from the videogame series Warcraft, made his first appearance in Warcraft III: Reign of Chaos, and is the final boss of the Wrath of The Lich King expansion pack of the massive online roleplaying game, World of Warcraft. To unlock Arthas in Warriors of Rock, the player must reach rank 71 in Quickplay+ by collecting a total of 1600 stars. Unlocking him also unlocks the Frostmourne guitar, designed after the sword with the same name from the Warcraft games, wielded by The Lich King.