Dark spirits are entities who have become unbalanced due to the influence of the spirit of darkness and chaos, Vaatu, who uses their anger and other negative emotions against them. However, even after Vaatu was locked away by Avatar Wan, spirits could still become dark. By Avatar Korra's time, many spirits had grown restless due to the destruction of a spiritual forest in the Northern Water Tribe and had managed to cross from the Spirit World to the mortal world, attacking both the Northern and Southern Tribes as vengeance for this act. However, Korra was able to unlock the South Pole's spirit portal, causing these spirits to disappear, though other dark spirits still remain in the physical world. They attack seemingly at random, with some lurking in sacred areas that have become neglected