is this a cartoon?
Yes
Marceline the Vampire Queen
Marceline the Vampire Queen is a fictional character in the American animated Cartoon Network television series "Adventure Time", created by Pendleton Ward. She is voiced by Olivia Olson in most appearances, by Ava Acres as a child and by Cloris Leachman as an old woman. Marceline is a fun-loving 1,000-year-old vampire queen, as well as a musician who plays an electric bass that she made from her family's heirloom battle-axe. The artistic design for Marceline was created by Ward, with small changes and additions added by Phil Rynda, former lead character and prop designer for "Adventure Time".

who does the voice of marceline on adventure time Olivia Olson who is marceline? Marceline the Vampire Queen is a fictional character in the American animated Cartoon Network television series "Adventure Time"
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Marceline the Vampire Queen [SEP] Introduction
However, as the series progresses, Marceline becomes a close friend to the two. Several backstory episodes have established that she was born to an unnamed human mother (voiced by Rebecca Sugar) and the demon Hunson Abadeer (voiced by Olivia's real-life father, Martin Olson). Furthermore, when she was a child, the cataclysmic Mushroom War occurred, and soon after she developed a father-daughter-like bond with Simon Petrikov (voiced by Tom Kenny), who would one day turn into the Ice King. Marceline has been critically acclaimed and is popular with the "Adventure Time" fandom. The character was also the focus of the seventh season miniseries "Stakes" (2015).