You need to monitor both the content and the amount of TV that your boy watches, regardless of the nature of the programming. Passive TV-watching is not a healthy activity for kids in anything but small doses.

The fact that he uses ghosts, aliens, and soldiers as heroes does not mean that he will be a violent child or adult. However, repeated exposure to violent TV, video, computer, and movie images will lead him to accept violence as an exciting way to solve problems and relate to others. Pick up a copy of Steve Bennett's Kick the TV Habit as a resource to help you establish sensible TV-viewing habits for your son and your family.