Here's why:
* Gothic Aesthetics: Dark hair aligns with the gothic and romantic aesthetics that often accompany vampire stories. It contributes to a mysterious, brooding, and alluring image.
* Contrast with Pale Skin: The contrast between dark hair and pale skin (another common vampire trait) is visually striking and emphasizes their "otherworldly" beauty.
* Classic Portrayals: Many classic and influential vampire portrayals in literature, film, and television have featured female vampires with dark hair (e.g., depictions of Dracula's brides).
* Symbolism: Dark hair can be symbolic of darkness, mystery, and even danger.
However, it's important to remember that there are plenty of exceptions. Some notable vampires have had blonde or red hair. Ultimately, the hair color of a female vampire depends on the specific story and the creator's vision.