These days, any TV show or movie that wants to create horrors not of this world are going to rely pretty heavily on visual effects and CGI to defy the usual laws of physics. In these two videos, you can see how the ones from Constantine's episode two and episode four were built.
In the above video, for "The Darkness Belief," there's a moment where a normal hand grabbing a face in a car — which is more humorous than scary — gets an evil makeover. A thin line of VFX separates farce from horror.
[via Dread Central]