I feel there is a difference between fascination and obsession - do you feel these thoughts are affecting your ability to function? Its not unusual to think about death often - there are plenty of things to remind us of our mortality. I certainly don't think popular music or television shows etc help, death has been somewhat glamorised, made into something its not. All i can suggest is that if you find these thoughts troubling please seek out a therapist and work through this problem with them. All the best.