That Time I Got Reincarnated as a Slime: Every Great Demon Lord, Ranked By Strength

Highlights

• Octagram, formerly known as the Ten Great Demon Lords, now consists of only eight powerful beings led by Guy Crimson.
• Each member of Octagram has unique skills and offensive moves, ranked based on their strength and abilities in combat.
• Rimuru Tempest, the Carefree King Of Monsters, has risen to become a true demon lord due to his creativity and magic prowess.

In the world of That Time I Got Reincarnated as a Slime, the demon lords are considered the most powerful beings on the planet. Not many people know what they look like, but everybody mentions their names with fear, respect, and admiration.

They used to be known as the Ten Great Demon Lords, but thanks to new upstart Rimuru Tempest, there are only eight of them now. Nowadays, they go by the name of Octagram, an eight-pointed star. Based on the power they’ve displayed in the series, here’s every member of Octagram, ranked based on their strength.

Updated July 23rd, 2024, by Harry Nugraha: This update adds more relevant details to every entry on this list, such as information on the Most Powerful Skill and the Strongest Offensive Moves of each character. Most Powerful Skill refers to the best skill within the character’s arsenal. Some of them are Ultimate Skills, like Dino’s and Rimuru’s, but there are also some powerful Intrinsic Skills, such as Ramiris’s and Dagruel’s. Most of these skills are related to combat, but there are also some that specialize in other areas, such as Ramiris’s skill which focuses on creation, or Rimuru’s skill which focuses on analytical ability and skill manipulation.

That’s why we also add the Strongest Offensive Moves, which refers to each character’s strongest attacks. Some of them already appear in the anime, but most of them are still exclusive to the original light novel. Some of these offensive moves are a form of powerful battle arts, such as Leon’s and Luminous’, while others are a form of nuclear magic, such as Guy’s and Rimuru’s.

8 Ramiris

The Cheerful Queen Of Fairies

• First Appearance: Episode 22
• Most Powerful Skill: Small World
• Strongest Offensive Moves: Summon Greater elemental of Earth: War Gnome

When it comes to physical prowess, the fairy queen Ramiris is the weakest in the group. Her body is the size of an adult hand, and her physical strength is comparable to her size. Although she can fly, her speed and maneuverability are limited. A regular human could hurt her with a flick of a finger.

Ramiris became a demon lord due to her special ability. As a fairy queen, Ramiris possesses a skill known as the “Labyrinth Creation,” which allows her to create and manipulate underground labyrinths. From adding and resizing the floors in a matter of seconds to creating any kind of environment within each floor to crafting all kinds of powerful golems, Ramiris can do anything as the Labyrinth master. And, as long as she is inside the labyrinth, she is nigh immortal and invincible.

7 Leon Cromwell

The Stern Former Hero

• First Appearance: Episode 6
• Most Powerful Skill: Surya, Lord of Brilliance
• Strongest Offensive Moves: Hundred Breaker

Leon Cromwell is a stern, quiet man who rules over the faraway land of El Dorado. Like Rimuru, he is also an otherworlder, summoned from Earth long ago. He even managed to become the Chosen Hero during his early years in this new world. However, he abandoned that heroic path hundreds of years ago, and has evolved into a being known as a demonoid. Leon was the one who summoned Shizue Izawa, Rimuru’s friend and Hinata’s mentor.

As a ruler, Leon rarely engages in combat. But when he does go to the battlefield, he has the power to push back against one of the Primordial Demons who often disturb his domain. He earned his seat as one of the Demon Lords by killing the previous demon lord, the Curse Lord Kazalim. Although he is not as strong as the other members of Octagram, his strength is nothing to scoff at.

6 Luminous Valentine

The Queen Of Vampires

• First Appearance: Episode 45
• Most Powerful Skill: Asmodeus, Lord of Lust
• Strongest Offensive Moves: Memory End Requiem

Luminous Valentine is the soft-spoken, cunning queen of the vampires who rules over the Holy Empire Lubelius. Although she is the queen of the Empire, the citizens of Lubelius never know about her existence. That is because she used one of her close subordinates as the public face of the Empire.

On the outside, Luminous looks like a chic teenager. But despite her innocent appearance, she can easily destroy a house with her bare hands. She also possesses all kinds of magic skills that are unique to her kind, such as Charm and Life Drain. Luminous is a master in using Holy Magic, even though she is a vampire, a creature of the dark. From disintegrating unholy creatures to bringing the dead back to life, Luminous has achieved the pinnacle of Holy Magic.

5 Dagruel

The King Of Giants

• First Appearance: Episode 45
• Most Powerful Skill: All Things Destruction
• Strongest Offensive Moves: Maelstrom Buster

With his towering physique and charismatic presence, Dagruel is the most stoic-looking member of the Octagram. As the King of the Giants, he rules over the Barren Land at the westernmost part of the continent. He is a wise King who is both feared and admired by his people. Even the other Demon Lords have nothing but respect for Dagruel.

As the mightiest warrior of the Giants, Dagruel’s physical prowess is second to none. Even without using any of his intrinsic skills, he can pulverize an enemy with his fist. He can even go toe to toe with the Storm Dragon Veldora. Veldora at his full power will dominate the Giant King, but Dragule can hold his own during a regular brawling session with the True Dragon, a testament to how formidable Dragule is.

4 Dino

The Sleepy Fallen Angel

• First Appearance: Episode 45
• Most Powerful Skill: Astaroth, Lord of Fallen
• Strongest Offensive Moves: Fallen Crusade

Dino is by far the most mysterious member of the Octagram. He has messy hair, a disheveled appearance, black rings under his eyes, and he always slumps back and falls asleep during Demon Lords meeting. This disorganized lifestyle earned him the nickname the “Sleeping Ruler.” Dino is the only Demon Lord who doesn’t have, and never wanted to have, a territory under his rule.

Dino comes from a race known as the Fallen Angels. In actuality, Dino was one of the Seven Angels of Origin, the first living beings created by the king of creation himself, the Star King Dragon Veldanava. As such, Dino boasts enough power to destroy an entire nation with a single strike. Thankfully, for the past few thousand years, Dino decided to seal his power and assume the role of a watcher instead. He’s still more powerful than most, but his current strength is far from his true power.

3 Rimuru Tempest

The Carefree King Of Monsters

• First Appearance: Episode 1
• Most Powerful Skill: Azathoth, God of the Void
• Strongest Offensive Moves: Abyss Annihilation

Rimuru Tempest is the newest addition to the Demon Lords ranks. In a short time, he evolved from a lowly Slime to a true demon lord. The fact that he is an otherworlder plays a huge part in his shocking rise to power, but at the end of the day, it is his creativity and daring personality that helped him reach such a great height.

As a slime, Rimuru doesn’t boast great physical prowess. He can knock people out with his punches, but his true strength lies in his magic. With the help of his Ultimate Skill, Lord of Wisdom Raphael, Rimuru has reached the pinnacle of magic. One of his Crown Jewels is his original magic, Megiddo, the first and only physics-based magic in the world. With Megiddo, Rimuru can shoot laser beams that can pierce any defense, or create a surveillance camera that allows him to see every corner of his nation.

2 Milim Nava

The Chaotic Daughter Of The Star King Dragon

• First Appearance: Episode 16
• Most Powerful Skill: Satanael, Lord of Wrath
• Strongest Offensive Moves: Drago Nova

Milim looks like a regular, energetic teenage girl. She has a bright smile, twin ponytails, petite body, and cheerful and carefree attitude. But when it comes to physical strength, she can hit as hard as Dagruel, fly as fast as Luminous, and battle as bravely Veldora. The girl finds joy in an intense battle, especially one where she can go all out without having to worry about destroying a mountain or two.

Despite being the daughter of the legendary Star King Dragon Veldanava, Milim is not a True Dragon. Because her mother is a human, she is considered a Dragonoid. That being said, her innate power is already among the highest in the world. Like Draguel, Milim is perfectly capable of going toe to toe with Veldora in a sparring session. As if that’s not enough, Milim can also access her True Dragonoid Form, where every single one of her abilities is enhanced to the absolute limit.

1 Guy Crimson

The Almighty Primordial Demon

• First Appearance: Episode 42
• Most Powerful Skill: Lucifer, Lord of Pride
• Strongest Offensive Moves: Death Streak

The leader of the Octagram and the most fearsome being in the entire world is Guy Crimson. Guy is the most powerful Primordial Demon and also the first Primordial who crosses over to the mortal realm. He was there during the time of Veldanava and even managed to earn the Star King Dragon’s recognition. After the Star King Dragon’s passing, Guy becomes an acquaintance/rival with Veldanava’s protégé, the Emperor of the Eastern Empire, Rudra Nam Ul Nasca. They have been battling and outwitting each other for centuries, and won’t stop anytime soon.

When it comes to pure physical power, Guy is far above Milim, the second-best in the world. In terms of magic, Guy is way more powerful than Rimuru. Rimuru’s magic may be more advanced and intricate, but none of it matters in the face of a colossal amount of magicule that Guy can throw around at will. Guy can easily defeat a full-powered Veldora. He even engaged in a no-holds-barred battle with Veldora’s older sister, the Frost Dragon, Velzard, which ended in a draw. This battle was so destructive that it shifted the center of the world. Yet after this battle, Velzard ended up becoming Guy Crimson’s trusted partner to this day.