Lich

The lich is a powerful undead creature. A lich is a person who has sacrificed their life, in return for immortality. The soul of the lich is bound to an object known as a phylactery. As long as the object remains intact, the lich can never truly be vanquished. While the rituals could be perfomed on others by a necromancer, most cases paint the lich as magic users themselves. While the state of decay may vary, the lich usually appears as either skeletons or ghosts. While many forms of undeads have little or no intelligence, becomming a lich in turn, increases the potential capabilities of the mind.

Source
The modern lich, as a powerful undead sorcerer, while made popular by Dungeons & Dragons, can be traced back to short novellas such as Skull-Face from 1929. The word itself is older, but was previously used simply to describe corpses or a general term for the undead.

Media
Liches appear in the following media:

Games

 * Castle Age
 * Crypt of the NecroDancer
 * Castle Age
 * Crypt of the NecroDancer
 * Crypt of the NecroDancer
 * Crypt of the NecroDancer