Many Halloween traditions revolve around spirits who comes back from the dead. After all, Halloween descended from Samhain, a time when the boundary between the world of the living and the world of the dead becomes thin and blurred. This focus on the dead gives us the folklore surrounding ghosts, vampires, and zombies -which we think of as scary. But it wasn't always so, at least for ghosts.
The ghost stories we see in horror films are designed to be terrifying, usually involving a spirit who has unfinished business in the corporeal world that requires that they scare the daylights out of us. Conversely, there are the Star Wars force ghosts, who are brought back to showcase familiar characters who died before their popularity did. But I digress...
There's no real mystery why ghost stories have been around so long. People have a hard time letting go of those who died, and the fear of death leads us to look for some evidence of an afterlife. In ancient times, ghosts weren't all that scary. Early European stories featured ghosts who didn't try to frighten those they appeared to, but rather to communicate with them. So how did such benign ghosts become fodder for campfire tales and horror films? That took hundreds of years and the influence of Christian theology. The result was that modern ghosts come in all forms. Of course you are familiar with malevolent ghosts of horror films, but there are also the helpful ghosts of A Christmas Carol, the funny ghosts of Ghostbusters, romantic ghosts like Patrick Swayze's character in Ghost, and the nod to nostalgia in Star Wars movies.
Read about the evolution of the ghost story and what it means at Perspectives on History. -via Strange Company