Marceline is a character from the Adventure Time series. She is a fun-loving and mischievous 1,000-year-old vampire Queen. Marceline plays an electric bass, which she made from her family's heirloom battle-axe as revealed in "It Came from the Nightosphere", and occasionally plays musically with Finn and Jake. Unlike most vampires, she reveals that it's the color red she likes to suck out of various things, and blood is only appealing because it is red. Like a traditional vampire, she is vulnerable to sunlight and is capable of turning into a bat, varying in size. The show generally portrays her as a close friend of Finn and Jake, but she often feels alone as depicted in "Marceline's Closet".
It is confirmed that she had a homosexual relationship with her ex-girlfriend Princess Bubblegum.