Vampire mesmerism refers to the ability of a vampire to manipulate the mental, physical and/or emotional faculties of a human being, or in some cases, another supernatural creature. Ever since Bela Lugosi first wagged his magic fingers in 1931's Dracula, vampires have ever since been depicted as possessing some version of this ability. The degree with which a vampire can control the thoughts or actions of another is often in direct proportion to the vampire's overall power level, which is usually based upon age. An older, more experienced vampire can mind control someone with greater reliability than one who had only recently been made into a vampire.
Vampiric mesmerism is used a plot device to not only enhance the tension of a scene, but also to provide a means by which a vampire can continue to function indiscriminately without arousing the suspicions of others. Most often, this power is used when a vampire is seeking to drink blood from a victim and doesn't want to deal with all of the hollering and shrieking. Pesky mortals.
Naturally, the ability to mentally manipulate another has a tendency to be abused. Horny Bulgarian vampire, Count Yorga, was known for exercising his power in just such a fashion. He used vampire mesmerism to seduce a woman named Erica Landers. After putting the bite on her, Yorga's control over Erica strengthened. He also used this power to force his other vampire courtesans to make out with one another. Additionally, he had Erica lustfully massage her own breasts. It's good to see that once in a while, a vampire finds ways to actually derive pleasure from this particularly invasive ability. [1]
An Asian cult leader named Chin Yang used this ability to evade the efforts of a Scotland Yard inspector named Murray. Distracting him by stating that she was an unwilling participant in a cult founded by Count Dracula, she then tried to seduce Murray. When she bore her fangs however, Murray broke free of her control, wrestled her to the ground and drove a stake into her heart. [2]