|Voiced by||Arthur Kade|
Marshall Lee is the gender-swapped version of Marceline, created by the original series designer, Natasha Allegri. Like Marceline, he is a vampire, and is feared by Cake like Marceline was feared by Jake. As the counterpart of the Marceline the Vampire Queen, Marshall Lee is the Vampire King in the gender swapped universe. Like Marceline, it is unknown how he became a vampire exactly.
Marshall Lee has pointy ears and blue skin like Marceline, but his initial character model is green, as it was used in a scene with a special lighting. 
His hair is shorter than Marceline's but he has a matching permanent bite mark. The bite mark however, is on the opposite side of his neck. He initially wore a grey plaid shirt, but now wears a red and black plaid shirt. He also wears dark blue jeans, and brownish-white sneakers.
- Marshall Lee's skin is green because of lighting, according to Natasha Allegri's Formspring.
- Marshall Lee is the Vampire King in the gender-swapped episode.
- Like Marceline and Princess Bubblegum, Marshal Lee may have a form of friendly rivalry with Prince Gumball.
- Marshal Lee may have mother issues as Marceline has father issues.
- He and Marceline both have regular electric bass guitar, as seen in the openings.
- According to Natasha Allegri's Formspring, Marshall Lee will be voiced by Arthur Kade. 
- Marshall Lee was suppose too say "What, your in a dress!!!! That's crazy sonn." This got cut out for timing