Marshall Lee

Marshall Lee (full title Marshall Lee the Vampire King), is the gender-swapped version of Marceline, created by the original series designer, Natasha Allegri and featured in "Fionna and Cake." Cake is scared of him just like Jake was scared of Marceline.

Abilities
Marshall Lee supposedly has the same abilities as Marceline, since his screen time showed him floating.

Appearance
Marshall Lee has pointy ears and light blue skin. An alternate character sheet depicts him with green skin, but it was only used in one scene with a special lighting.

His hair is shorter than Marceline's but he has a matching permanent bite mark. 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.

Though Marceline has circle-shaped eyes, his eyes are rectangular. Unlike Marceline's forked, snake-like tongue, Marshall Lee's tongue is rounded.

Personality
Personality-wise, Marshall Lee should be similar to Marceline. He appears to have an interest in music like Marceline, as he's shown to own a guitar and he gave Fionna the devil horns, a popular hand sign amongst heavy metal and rock n' roll fans.

Trivia

 * He and Marceline both have regular electric bass guitars, as seen in the openings.
 * Rebecca Sugar said that she fought for Marshall Lee to have a few lines (such as "Whoa, Fionna! You're wearing a dress? That is cra-azy, son!), but they were cut for time. She wanted him to be voiced by Dante Basco.
 * Marshall Lee floats leaning backwards, back to the ground, and knees bent whereas Marceline floats, knee back, chin up, and leaning forwards.
 * Marshall Lee had 10-11 seconds on screen.
 * In an interview with Pendleton Ward at Comic-Con, he stated that the next genderbent episode would mostly focus on Marshall Lee.
 * Pen officially addressed Marshall Lee as "Marshall Lee the Vampire King."
 * Marshall had 5 fingers when he gave Fionna the "Rock On" sign, but he must only have 4 fingers like Marceline.
 * Some of the artwork depicts him in a gray plaid shirt, which looks similar to the one Marceline wore in the episode Video Makers.
 * Zack Shada said that he would like to apply for the voice of Marshall Lee since he had been on the Adventure Time pilot voicing Finn from the pilot back in 2008.
 * Marshall Lee should be 18-21 years old biologically since his gender-swapped counter part is:Marceline.
 * Marshall Lee's plaid shirt may correspond with Marceline's red and black striped shirt from It Came from Nightosphere
 * He will be appearing in another genderbent episode but its unknown if Zack Shada or Drake Bell will do the voice.