Is addiction for horror movies a mental issue ??

Depends: Hi Sri, some people are just wired to enjoy this kind of arousal. In principle, you can become addicted to almost anything, and it is unhealthy if becomes the primary coping mechanism and is accompanied by compulsion/dependency. If concerned, I suggest the individual consult a mental health provider for full eval. If it has become an addiction, it can be reversed with treatment. Take care

Horror movies: Yes, addiction for a Horror movie may cause a mental issue. I strongly recommend that you have your primary doctor refer you to a Psychologist. She/he will help you.

Definitions: Mental health professionals may treat it and they'd find a DX for the case. Any addiction is a combo of behavior habits, physical need for pleasurable chemical intake or release, the emotional reactions to all of it and the thoughts learned to associate w/ the specific 'thing' - in your case horror films. You can find ways to gain control. You may have other issues, but this is not being crazy.