A lich is an undead sorcerer, often one who seeks Immortality or power above anything else, and became undead as the price he had to pay. Typically his soul is stored elsewhere in a Soul Jar, at times called a phylactery, which must be destroyed before he can be fully defeated. In other fiction, the Soul Jar is optional. A lich's physical appearance can range from near-normal, to zombie/corpse-like, to completely skeletal, which usually depends on the lich's age. Because of their skill at magic, liches tend to be the most powerful and dangerous type of undead in settings where they exist.