Vampires in the terms of Hollywood and fictitious books (such as the Underworld movie series, Bram Stoker's Dracula, Twilight Saga, and the vampire books by Anne Rice) are just that - fictitious. They are not real.
There's some debate about a form of vampirism concerning energy. These would be Psi-Vamps/Psychic-Vampires. People who need to "feed" off the energy of others to actually feel normal, be healthy, and all. However, there are those who will intentionally take the energy of other people just because they can when they have no dire need to do so. These people also call their selves Psi-Vamps.
The debate in this comes from the matter of leechers who take energy without a true, honest need for doing so. They call their selves Psi-Vamps just because they can take from the energies of others. But the truth of the matter is that they could take energy from other sources; such as the sun, the moon, elements, earth, etc. Yet they choose people. To do so in such circumstance is highly looked down upon. From what I've seen, they call them selves as such because they think it's cool and good way to claim to be a vampire without being called fluffy or a role-player.
Either way you look at it, leeching of energy is leeching of energy, whether it be out of need (which is commonly done subconsciously by the legit Psi-Vamp) or just because they can (commonly done consciously by the those who choose to do so because they can.)