“The lich is, perhaps, the single most powerful form of undead known to exist. They seek to further their own power at all costs and have little or no interest in the affairs of the living, except where those affairs interfere with their own.
A lich greatly resembles a wight or mummy, being gaunt and skeletal in form. The creature’s eye sockets are black and empty save for the fierce pinpoints of light which serve the lich as eyes. The lich can see with normal vision in even the darkest of environments but is unaffected by even the brightest light. An aura of cold and darkness radiates from the lich which makes it an ominous and fearsome sight. They were originally wizards of at least 18th level.
Liches are often (75%) garbed in the rich clothes of nobility. If not so attired, the lich will be found in the robes of its former profession. In either case, the clothes will be tattered and rotting with a 25% chance of being magical in some way” The Monstrous Manual, 2nd Edition