Marceline the Vampire Queen is a half-demon, half-human vampire character from the show Adventure Time. She became the Vampire Queen after killing the previous Vampire King before the show begins, even though she's over 1,000 years old, she looks like an 18- to 21-year-old. Marceline has gray skin, pointed ears, and demonic qualities, and she can also transform into monsters like bats, wolves, and tentacle beasts.