Demon King

The is the king of the Demon Clan. He is the one who handpicked the Ten Commandments and granted them their Commandments.

Appearance
Though the Demon King's true appearance has yet to be seen, he appears before Meliodas as a massive shadow made of darkness.

Personality
He seems to be quite relaxed and forgiving, causally talking to Meliodas and playing along with his bluffs even though he was a traitor to his clan. He shows much distaste towards the certain woman who had changed Meliodas, but is very confident and elated at the thought about eventually being able to convert his son back to the side of the Demon Clan.

3,000 years ago
The Demon King fought against Meliodas who was accompanied by Gloxinia and Dolor prior to their eventual defection to the Demon Clan and was defeated by them. At one point he cursed Meliodas with immortality, causing him to be unable to die regardless of the method used to kill him.

Current arc
After Meliodas's fight with the Ten Commandments, the Demon King greets him in Purgatory. He admits to having been keeping an eye on the captain of the Seven Deadly Sins throughout and muses that even Meliodas was unable to do anything other than wait for death when caught by the Commandments of Piety and Love. When Meliodas counters that he is now free from the Commandments' bindings thanks to his curse, the Demon King agrees but mentions that he can feel Meliodas' quivering. Entertaining Meliodas' bluffs, he expresses anger towards the certain woman who had changed Meliodas and then informs him that though he was left in a greatly weakened state, the curse he casted on the Dragon's Sin of Wrath would allow him to feed on his emotions everytime he dies, allowing the Demon King to regain his lost power and at the same time reverting his traitorous son back to the state he was three thousand years ago. He is then attacked by an outraged Meliodas.

Abilities and Equipment
The Demon King is extremely skilled with blessings and curses, having been the one who created the Commandments that the Ten Commandments wield. He is also responsible for the seemingly unbreakable curse on Meliodas that has lasted for at least three thousand years.

He is also incredibly powerful enough to be the leader of the entire Demon Clan, followed by his three sons who inherited his strength.

Meliodas
The Demon King appears to be rather forgiving towards Meliodas, conversing with him casually and entertaining his bluffs. Despite Meliodas being a traitor to the Demon Clan, the Demon King still desires for his son to regain his strength and return to their side.