...reviewing all the monsters, you'll notice there's only one decent monster that starts with V. Unless you count the Vargouille, which is a type of vampire.
The usual problem with vampires in D&D is squaring the typical (and very interesting) conception of a vampire as a spooky Machiavellian subtle horror movie monster with the fact that the easiest thing for a vampire to be in D&D is a guy just like you who hits you with things and can turn into a wolf or a bat and is really hard to kill. Basically a sort shape changing Goth-themed super villain
I'll just record a few rules you might be able to use to make a spookier vampire:
A vampire can never (and knows it can never) touch the same victim twice--so if it goes after you, it's going all the way.
A vampire can never appear to the same person in the same form twice--so you never know if you're fighting the vampire or just one of its minions.
A vampire can never change shape in front of anyone else and if reduced to 0 hp it will have to be rescued.
My best shot at the vargouille was this.