Marceline the Vampire Queen is a fictional character from the animated television series Adventure Time. She is a half-demon, half-human vampire who has a unique ability to absorb the color and life force of others. Marceline is known for her love of music and often plays her bass guitar, expressing her emotions through songs. Marceline has a complex personality, showcasing both playful and serious traits. She has a close friendship with Finn the Human and a romantic history with Princess Bubblegum. Her character explores themes of identity, love, and the passage of time throughout the series.