My favorite Count Dracula costume idea would have to be the mysterious, handsome, old school Dracula version. Not the super creepy Gary Oldman movie version.
My favorite Dracula Halloween costume would include of course, a cape. A cape that is black but with red velvet inside and a stand up collar. A medallion of some kind that gives Dracula power and a touch of royalty would be a nice touch too.
Also he would need to have a white pale face, dark circles under the eyes, red lips, dark black slicked black hair and fangs. The fangs would be the key, they would have to be pointy and somewhat realistic looking. Blood on the mouth would make it spooky.
The costume clothing would be black pants, black or white shirt and/or vest, and black dress shoes. A good costume would include some creepy vampire hands, pointy nails, dark lines and veins on the skin. Think about Fright Night or Buffy the Vampire Slayer (The Master) creepy hands.
The costumed Dracula could go by names like Vlad, Dracula, the Count, etc. What would enhance the costume is to "act" and show fear at crosses, holy water, wooden stakes, etc. Or you could go in a group and have other dress like bite victims, other vampires, etc.
There are many other versions of movie or TV Dracula's you could use for inspiration. Such as the original Bram Stoker Dracula (Bela Lugosi), Christopher Lee (1970's version), Christopher Plummer, etc. For TV, you could go for the young, handsome one from Buffy. Any of these ideas will make a scary Halloween and a spectacular Dracula costume
" I can smell the sunlight on your skin." -- Bill, True Blood