Wraith
Wraith is a black creature subtype used for cards that depict spirit-like apparitions that are supposed to portend the death of their beholder.
The first card to bear the type was Bog Wraith in Alpha. Other examples include Dirtwater Wraith, Bog Tatters and Street Wraith from Future Sight.
Odyllic Wraith used to be subtype Undead but this was changed to Wraith in the Weatherlight online release.