Malladus, the main antagonist of the game The Legend of Zelda: Spirit Tracks, is the Demon King and enemy of the spirits. Years ago, after a war between the spirits and demons, Malladus was sealed beneath the ground. The spirits used the Spirit Tracks as shackles, stretching across the land. In the center of the Spirit Tracks, the Tower of Spirits acted as a lock.
The Legend of Zelda series
The Legend of Zelda: Spirit Tracks
Malladus was freed when Chancellor Cole destroyed the Tower of Spirits. The pieces of the Tower were only kept intact by the magic of Anjean the lokomo. After stealing Princess Zelda's body, Cole and Byrne take the Demon Train and resurrect Malladus. After Malladus was resurrected in Zelda's body (because she was the only one with the royal blood of Hyrule), Malladus betrays Byrne, escaping the Tower of Spirits from Link and Zelda with Cole on the Demon Train. In the final battle, Malladus is forced out of Zelda's body by the Bow of Light, revealing his true form as a blue, floating skull. He then consumes Chancellor Cole to transform his body into a giant, blue monster. He is defeated when Link and Zelda stab the Lokomo Sword through his head.