Do not forget that you may might like to include a ghost in one of your stories, a character who has passed from the world of the living, but who will not actually leave!
Ghosts come back in a variety of shapes. Some are simply drawn, almost like a bed sheet floating in the air. The ghost above is very nice when you see right through him. Transparency accentuates his spirit form.
Alternatively, a ghost may still have color and even retain the appearance of her form from when she was alive—although putting something like long locks of hair up in the air gives a wonderful feel of being “other worldly.”
One of the most frightening ghosts is the one who returns from the grave dressed in a dark cloak and cold chains. His skeleton rattles when he walks, of course!
Remember the world of the non-living when you are looking for story characters. They are just as eager to be included in stories as all of the living characters!