A vampire full name: Marshall Lee the Vampire King), is the gender-swapped version of Marceline (the vampire queen) from the tv show adventure time. he was featured in "Fionna and Cake." episode from season 3 episode 9.
Mark:"hey did you see the new adventure time episode with Marshall lee?"
Stacy:"yeah he was the vampire right?"
Mark:"yeah he's the gender swapped version of marceline"
Stacy:"oh right it seems obvious now"