Marshall Lee is a half-human/half-demon, turned into a half-vampire/half-demon after killing the previous vampire queen many years ago and he is a fun-loving and playful 1,000-year-old vampire king. Marshall Lee is also an avid musician who plays an electric bass guitar, which he crafted from his family's heirloom battle-axe. Marshall Lee describes himself as a villain, fitting the part as he is rowdy, and endangers others with his violent, "friendly" rough housing. He can be mischievous, independent, and a "fearless" daredevil, but he still means well to others.

If you want to know more and voice him then check out the following link: Bad Little Boy | Adventure Time HALLOWEEN | Cartoon Network