Having an intense fear of Halloween is termed samhainophobia. The term comes from the Celtic word "Samhain," which was a harvest ceremony in which some people wore costumes and masks. When someone is not abnormally fearful of Halloween, then he likely doesn't have this phobia but may just dislike Halloween in general, as noted by Forbes.
Being afraid of Halloween is especially common among children, who can find scary masks and decorations fearful. Furthermore, some kids are scared of strangers and may be scared of going from house to house for candy. Those who have samhainophobia have a much more intense fear and feel they're in danger, even though there is none. This phobia is treatable with therapy, medication and relaxation techniques, as reported by Forbes.