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.
- He and Marceline both have regular electric bass guitar, as seen in the openings.
- Marshall has no speaking parts in the episode. Natasha Allegri stated on Formspring that Marshall Lee was voiced by Arthur Kade. However, she was joking just to see if a Arthur Kade Wikipedia page would be created.
- Rebecca Sugar said that she fought for Marshall Lee to have lines, but they were cut for time. She wanted him to be voiced by Dante Basco.
- Though Marceline has circle-shaped eyes, his eyes are rectangular.
- The name "Marshall" is of French origin and means "horse-keeper."