Tak

Tak is the invisible, incorporeal antagonist of Stephen King's Desperation and The Regulators - it can't take physical form by itself and must possess others in order to manipulate the world but is a diabolical force with inhuman intelligence and cunning: Tak is similiar in some ways to the true form of Pennywise (which is known simply as "It"), except for the fact that Tak isn't able to manipulate the world as easily as Pennywise and requires hosts to achieve its goals.