A wraith is a form of undead found mostly in fRPGs. The word itself derives from a Scottish word for a ghost or spirit, but the creature depicted is usually more cohesive, proactive and malicious than either of those sources would suggest.
As commonly depicted, the wraith is a shadowy, insubstantial thing driven by malice and hatred that can feed on the "life energy" of the living (the actual mechanism depending on the fRPG system in use) - it may also have various other magical powers, but is likely to be powerless in, afraid of and often harmed by sunlight. Sometimes seen as similar to a wight with no physical body it may also be bound to the place of its death and/or burial. Origin stories include them arising from a slain (or merely decayed) wight, or occuring when a malicious ghost "evolves" by adsorbing arcane power from some external source. Professor Tolkein's Ring-Wraiths may or may not be a good example of the type - being the souls of nine Dunedain kings held in bondage by a lifetime of attachment to cursed artifacts.
Being insubstantial, these creatures are often immune to non-magical weapons - sometimes with the exception of those weapons made from silver or which have been consecrated in some way (for example by having a relic attached). As a result, they need to be used with care against parties who lack magical resources.
Game and Story Use
- Campaign tone is vitally important here - if all the PCs have magical weapons and can swat wraiths aside like so many "damned bats" it will be a very different matter to a low magic campaign where defeating one wraith will take careful planning and a certain amount of nervous tension.
- Very few GMs remember that, having no physical body, there is no earthly reason for these things to womble about in rooms and corridors when they can quite cheerfully pop out of walls, floors and ceilings more or less at will, not to mention strolling across the tops of pitfalls and other trap triggers.