Trivia. Guy is the de facto leader of the group, due to being a powerful Primordial and the first Demon Lord.
In the Reincarnated as a Slime anime, only Milim and Rimuru have been confirmed to be True Demon Lords. As this comes with a significant increase in power, those who have not ascended to Demon Lord must have their own ways of cultivating power.
He is the 97th leader of the Demon Slayer Corps known mainly as Oyakata-sama (お 館? やかた 樣 さま , Oyakata-sama? lit. "Master") by his subordinates and peers and is also the head of the Ubuyashiki Family.
Enmu ( 魘 えん 夢 む , Enmu?) was the primary antagonist in the Mugen Train Arc of Demon Slayer: Kimetsu no Yaiba. He was a demon affiliated with the Twelve Kizuki, holding the position of Lower Rank One ( 下 か 弦 げん の 壱 いち , Kagen no Ichi?).
There's no doubt that Diablo will be superior to Rimuru in terms of technique (due to 20k+ years of experience), but he's definitely inferior in raw power and Skills. Moreover, there's "Food Chain" which makes Rimuru stronger as his subordinates get stronger.
The Demon King is the main antagonist of the anime and manga series The Seven Deadly Sins. He is the supreme ruler of Purgatory who commands the Demon Clan and the creator of the Ten Commandments. He is also the father of Meliodas and Zeldris.
Barbamon - I see him as the weakest Demon Lord, but the best tactician of all of them.
Upper Rank 1: Kokushibo
The number one ranked Kizuki is the terrifying Kokushibo, whose six orange eyes mark him out as one of Demon Slayer's most striking character designs. He also bears a major resemblance to Tanjiro thanks to his red-tipped hair and flame-marked face, although that appears to be a coincidence.
1. Nezuko. Nezuko, also a part of our strongest characters in the Demon Slayer list, is one of the most powerful female characters in the anime. Just by being a demon, she is more powerful than all the human characters in the series.
The same thing. 魔王 (Maou) is Demon Lord but can also translated to Demon King. There are no indication Demon King ever used in the series whether it's official or fan translation tho. The one who can became Demon Lord are Monster and Majin.
Iruma is a 14-year-old human boy who was sold by his parents to the Demon Lord Sullivan, who adopts him as his grandson.
During his time in the spiritual realm, we learn that Diablo or 'Noir' was the strongest amongst the other primordial demons - his only worthy rival being Guy Crimson, otherwise known as 'Rouge'.
So far, the Demon King is chronologically the oldest being in the series. By being in Purgatory, where one minute is a year, that would make his 3,000 years spent there would lead to his age being over 1,576,800,000.
The Demon King cries that if the attack hits him again, Britannia will be damaged. However, Meliodas still sends the attack to the Demon King, defeating him once and for all.
Momiji. Momiji is a Tengu and the daughter of Hakurou. She goes on to fall in love with Benimaru, becoming his wife and bearing his offspring before his awakening.
Guy has fought both battles with Velzado and Veldanava even though he never won against Veldanava, he is still consider to be the second strongest behind Rimuru.
Veldora can technically be considered the weakest and strongest True Dragon in regards to his ranking with Velgrynd and Velzado.
By Chapter 204 and 205, Yushiro and Chachamaru are presumably the only demons still left alive. His name contains the Go-on'yomi reading of the kanji for "healing" (愈, ゆ?)|yu}}, "history, record" ( 史 し , shi?) and the Kan-on'yomi for "male child, son" ( 郎 ろう , ro?), common male suffix.
Akaza is an upper-rank-three Demon and one of the most faithful minions of the Demon king Muzan Kibutsuji. The Blood Demon Art that Akaza uses is known as Destructive Death. Using his ability, he can create destructive shockwaves at will.
Upper Rank 3: Akaza
His abilities make him a formidable foe, and he is feared by both demon slayers and demons alike. Akaza's unique ability is his incredible strength and agility, which allows him to move at lightning speeds and deliver devastating blows to his enemies.