Wight is an obsolete word for a human. It is used now only to give an impression of archaicism, for example in the works of J. R. R. Tolkien. Tolkien also used the word to denote human-like creatures, such as elves or ghosts (vetter). It is akin to other words of Old English origin usch as were and world.
In many fantasy fiction and role playing settings Wights are a form of undead creature.