King of Night

"Another human filth walks into my once dominion, you shall fall into darkness by breathing in the Demon Realm's breath."

- King of Night to Luz Noceda.

The King of Night or the King of the Nights is an demon in the Demon Realm, once revered as one of the realm's most terrifying and strongest demons collectively known as the Archdemons. As Archdemon, he has ruled the Northern Isles under an terrifying grip of madness and despair, more often the cause of the demonic horrors the Isles is known for. However despite his power and capabilities that is believed to be even beyond Emperor Belos, he was defeated by Samuel Colt with the partially-restored Calamity Sword during the Night War and bringing his Archdemon reign to an end.

After his defeat, the King of Night now remained sealed as an bodyless figure with only his own skull where he eventually ended up in the Boiling Isles inside an carnival as an prize, suggesting that his myth and legend is either not known in the Boiling Isles or was removed entirely after his defeat.