The band Ghost performs in a dark and gothic style, involving a lot of hooded silhouettes. Despite being a metal band, their image is relatively PG, compared to many other heavy bands and is able to cross over more mainstream audiences. They have a large following in the United States and are generally well received, with few complaints or negativity, although they do face some racism and homophobia due to their use of black magic imagery.
The most common type of ghost is the appearance of a deceased person, usually a friend or family member but also famous people and historical figures. These ghosts often show themselves in a visible form, can make noise or touch you and might even emit odours to let you know they’re around. They can be friendly or hostile and might show signs of their death, such as a cut on the neck in case they died of a slit throat.
Alternatively, ghosts may simply exist as an immaterial energy that can interact with the world around them, using their surroundings to create effects such as fog and mist or a lingering smell (like perfume or cigar smoke). They might phase through solid objects or enter people’s dreams. They might even occupy and manipulate physical objects or take on a physical form themselves.
Whatever the ghost’s purpose, it’s important to consider how it’ll be able to interact with your main character and what sort of effect that will have. It’s also worth thinking about whether your ghost will be a solitary spirit or if it will have a relationship with the hero/heroine and how that might develop over the course of the story.