The March of the Undead: Part 1 - the Vampires

The other day I wrote a little bit about vampires in popular media. What I didn't discuss was actually what vampires were. Vampires are undead, that is to say they are no longer living, yet they are not dead. They are more than automatons, though, retain their memories from their lives and retain their senses. They are generally stronger and faster than humans, but cannot be exposed to sunlight for fear of death, and they also have a strong aversion towards garlic and crosses. They have fangs - long canines for biting their victims, and can be killed by a wooden stake through the heart (but then, who can't be?). To power their bodies, vampires cannot eat as they did in life, but must subsist on blood. The other details vary from author to author.
The original vampire, Dracula, was a horrible man, Vlad "the Impaler" Tepec. He was a horrible man, who did horrible things. I mean what would you expect with the nickname "the Impaler"? Dracula has the ability to mesmerize his prey, can turn to mist and take the form of wolf or bat. His change from Tepec to Dracula came about through non-biblical.
The Anne Rice vampires are the creations of the first vampire, Cain of biblical fame. Each 'generation' is weaker than the one that sired it (made it into a vampire), but is just as susceptable to the things which destroy vampires. Like Dracula, Rice's vampires have the power of mesmerism over their prey. Unlike Dracula, some of the vampires survive on non-human blood, but their quality of undeath is less than when they subsist on human blood. It is unclear whether this is due to quality or quantity. Unlike Dracula in which there are only four vampires, in Rice's books there are dozens with the oldest vampires thousands of years old and of immense power, power enough for them to even withstand exposure to sunlight.
Blackwolf Games role-playing game, "Vampire: the Masquerade" (the game from the 90s) builds off of Rice's vampires but divides the vampires into clans. Each clan has it's own strengths and weaknesses. Some are bestial, some have heightened strength, etc. The game tones down the religious aspect, while at the same time broadening it. Now, crosses are less effective, but religious symbols form other faiths also work.
The "Buffy the Vampire Slayer" franchise handles vampires completely differently. Especially in the television series, vampires are just something for the main character to overcome. There is little explanation of their abilities or powers or origins. Notably, there is an episode where Dracula comes to sunny Southern California, and of course is slain by Buffy. Another major change is that the vampires change appearance when they are getting ready to feed. They go from looking like normal humans, to having engorged foreheads and extended fangs. The best way to describe vampires in this setting is "disposible".
In the Blade trilogy and Underworld trilogy, vamires are no longer effected by garlic, or by religious symbols. They've also embraced modern technology utilizing it to both help prolong their lives and end the lives of their enemies. The vampires have also taken on a longer world view, thinking in terms of centuries, instead of years. As a result of this, the vampire 'bosses' are extremely wealthy.