Scary characters are often shown with scars and missing limbs.
Mental illness can create some dangerous behaviors, but that doesn't mean it's okay to depict mentally ill people as monsters.
And people with developmental delays are neither funny nor frightening, as they are often portrayed.
Even vampires and werewolf legends may be based on the rare diseases, porphyria and xenodermaphobia, which made people avoid light and crave blood.
That kind of Halloween costumes and decorations may make it more difficult for people with special needs to be accepted in our society.