In Phantom Hourglass, the main villain is Bellum.
Bellum is a life-eating demon who serves as the central antagonist of Nintendo's 2007 Nintendo DS adventure. The story begins when Tetra is taken by the Ghost Ship and later found petrified. Link learns that Bellum has been draining life force from the Ocean King's world, forcing the Ocean King to live in human form and hide Bellum in the depths of the Temple of the Ocean King.
To defeat the creature, Link must collect three pure metals and have them forged into the Phantom Sword. The weapon allows him to survive the temple's spectral threats and confront Bellum. The final conflict occurs in multiple stages, including a battle in which Bellum possesses Captain Linebeck and turns Link's ally into an unwilling opponent.
Bellum is sometimes confused with Ganon, Vaati, or Malladus because each is a major Zelda villain, but they belong to different storylines. Bellum is specific to Phantom Hourglass and is closely tied to the Ocean King, Tetra's kidnapping, and the Phantom Sword.