Heartless (ハートレス, Hātoresu) are hearts corrupted by darkness and without a body or a soul. They serve as most of the battles and challenges that the player must go through in the Kingdom Hearts games. They come in a large variety of types, categorized by being Pureblood or Emblem, both reproducing by taking more hearts and transforming them into other Heartless. Emblem Heartless were artificially created and are labeled with a heart symbol. Pureblood Heartless are black shadow creatures with bright yellow eyes. The Heartless obey those with the will to control themHowever, in worlds too close to darkness, the Heartless get stronger and become uncontrollable. The Heartless' method of entering worlds is to use the corridors of darkness, an unpredictable pathway that interlinks many worlds.