No, vampires are make believe just like elves, gremlins, and the French.
Big foot is make believe. Aliens probably exist but we have not had any confirmed contact with them.
No, not possible. The human body cannot subsist on blood alone. Only certain bats can and they are pretty much just in south america.
Zombies exist but they're not dead, just regular people that are drugged and hypnotized. Witches were real but they were probably using science, the power of belief, and knowledge of herbs to "cure" diseases. When they weren't being burned up by the same townspeople they helped in the past, of course.
No and no