Hunson Abadeer

Marceline's father (also Marceline's dad as referred to by Finn, and the "Lord of Evil" as seen in design documents though not in the show itself) is a character appearing in "It Came from the Nightosphere". He is freed from the Nightosphere by Finn, who believed that Marceline and her father should be together. Marceline's father initially shared a shaky parent-to-teen relationship with Marceline that involved an evil rampage through Ooo, sucking the souls of many creatures such as the Fuzzy Friends, the Marauders, and the most of the penguins in the Ice Kingdom (excluding one penguin named Gunter). Marceline's father is ultimately defeated by Finn, who released all of the captured souls and sealed the deathless being back into the Nightosphere. Marceline's father managed to reaffirm his love for Marceline just before leaving.

Personality
He claims to be "completely evil" and is shown to be extremely rational, as well as cold and calculating. He also shows care for things he deems evil; on the animatic, it shows that he is commenting and observing how Gunter is the "...most evil thing he ever saw" before Gunter hit him in the face. However, he is not completely emotionless, as he is apparently moved by hearing his daughter's song.

Appearance
His normal appearance is that of a big, blue-skinned humanoid with pointed ears, fangs, demonic eyes, and wearing a dark business suit like the Businessmen. He has a second, monstrous head with a vertical mouth that usually hides inside his normal mouth. However, when he transforms, this monster head emerges and replaces his normal head. He has a pair of red boots just like Marceline. He also appears to have two tongues.

Abilities
Marceline's father is "deathless," apparently meaning that he is immortal. He is capable of stealing souls, shapeshifting, regenerating, and growing to tremendous sizes. He is very strong and flexible so his body can bend many ways making him extremely good at fighting. An example of this is, his ability to swing his leg behind his head, kicking people in the face who try to attack him; he calls it Karate Kick.

Marceline
Marceline is his daughter who had problems with him for stealing her fries. After coming out of the Nightosphere, he had an argument with her after taking her ax away. He claims that he is a better fighter during their battle when she attacked him. He realized Marceline's feelings toward him when he listened to the song about their relationship. Toward the end of the episode, they had a talk which fixed the problems between them, but was interrupted when Finn sent him back to the Nightosphere.

Quotes
-Marceline's Dad to Gunter -Marceline's Dad to Gunter
 * "Of all of history's monsters, you are by far the most evil thing I've encountered"
 * "No! You can't have MY soul! I don't even have a... Look just get in here."

Trivia

 * Marceline and her father are voiced by Olivia Olson and Martin Olson, who are actual father and daughter in real life. Martin Olson is also a writer who was staff writer for Penn and Teller, Rocko's Modern Life, Camp Lazlo, and Phineas and Ferb.
 * Marceline has been confirmed to have once been a normal human before she became a vampire and doesn't show many of her father's abilities. This may be because her father was once human as well before being transformed into what he is now.