|David Hopkins (well sorta)|
The Devil (Also known as Lucifer/Satan) is the supreme force of evil in the Jack universe.
Once one of God's most beloved creations, Lucifer was the one who suggested to God the act of creation, which eventually led to existance itself. However, Lucifer eventually rebelled against God, waging war with many of his fellow angels. However, he lost the war, and was banished from Heaven, residing in Hell. Now residing at the very bottom of Hell, the devil works to corrupt and tempt the living, to lead them astray and into the ways of evil, away from God.
Though the devil is the supreme force of evil, he seems to take little interest in Hell itself, or it's occupants, even stating in a hidden comic that Hell will one day have a new king, and that he can have it, implying that the Devil doesn't care about ruling the realm of the damned, though he is not above interacting with it, as the devil has directly punished two souls personally, and has talked with both Jack and Drip directly (though the interaction with Drip took place off screen). Though fallen, the devil still maintains a vast array of powers, including the ability to change form and gender, and the ability to temporarily travel to both Heaven and Earth.
It is worth noting that although the devil is the supreme force of evil, he, like other damned souls, has the option of leaving Hell, as God once implied to Central that the Devil can leave Hell when he apologizes for his sins and repents for them.