I have a much greater fear of the evil inherent in people than anything to do with the supernatural. I'd rather confront a malign spirit than a burglar in my living room any day of the week... I have existential fears as well, the concept of eternity bothers me.
And while I'm on the subject, I'm a bit afraid of the huge expanses between the planets. I have a recurring fear of being granted one wish and accidentally asking to be put on Pluto by myself. I actually struggle to look at pictures of the very distant planets but funnily enough I'm ok with the nearer ones. (Its a fear I'm happier sharing here than I would be with a psychiatrist!)
But any fears I do have, I'm very much in control of them. The best advice I can give anyone with a fear is to seek it out, confront it and familiarise yourself with it.
Image http://www.sxc.hu/browse.phtml?f=view&id=828669 (under_net)