Some of the Gua’uld (from Stargate) are pretty hot (or at least their hosts are). They definitly have demon-like qualities. They possess people for one thing. They are pretty much all evil, power hungry, and convinced of their own superiority. They even have a number of superhuman "powers" both in the form of natural abilities, and advanced tech.
Heh, for some strange reason I always had a thing for the Nocks (sp?) The fairy like people from earlier in the show. While not overtly "sexy" they had a very magical, mysterious quality to them. Innocent to a fault as well, which brings me to my next part

In the past couple months I've become very interested in Angels/Demons, but specifically Fallen Angels. Just something about a being so pure and innocent, choosing a path so dark and twisted. Almost all of the stories I've come up recently have featured this.