Spectre

The most frightening type of spirit are Spectres. Spectres are in many ways the malevolent counterparts of Ghosts and they seldom wish the living any good. The majority of Spectres remain behind due to being the victims of a horrible curse or by being an oath-breaker or other form of traitor. They are angry beings, full of malice for the living and despair at their own state.

Spectres are Spirits trapped in the mortal world as a result of a broken vow or a curse placed upon them. A few Spectres may make common cause with the living in the hopes relieving their condition and gaining freedom at last. The majority, though, have been driven mad, evil, or both by their years of torment and the knowledge that they helped bring it upon themselves. They attack the living out of pure malice, reaching their hands out from within walls or other objects to paralyze and slowly kill anyone that falls into their clutches.

Source

 * Warhammer Fantasy RPG 2nd ED -- Old World Bestiary pg. 67 110