What does a real ghost look like?

I've only seen one ghost and I described it in an earlier post about "photographs of real ghosts".  I only saw with peripheral vision (and heard) a ladies feet and skirt walking through the hallway of a house we rented.  My son, who was 2 or 3 at the time, saw her from a more head on point of view.  She just looked like a woman, it all seemed very normal at the time... as I write this 25 years (or so) later, at 11 PM it really gives me the creeps.
In the cinema I really get "spooked" by the more subtle hosts, not bright, flying ghosts with loud, echoing voices.
Below are photos of the scariest movie ghosts that I know of.

First is the ghost from the 1989 BBC movie, "Woman In Black"

Second and third are the ghosts from "The Innocents"

This fourth photo is Madeline O'Malley from the 2011 movie, "The Innkeepers"

Br-r-r-r! Good evening!