All spoilers regarding the first four story arcs (volumes 1-20) are unmarked. Examples pertaining to the fifth story arc and Shin High School D×D can be spoiler tagged if necessary.
This page details the various dragons in High School D×D.
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DragonsOne of the most powerful beings in the universe, dragons are created from large masses of energy. They are divided into several different classes and are also fond of hoarding treasure. In some cases, the dragons are sealed in Sacred Gears until the user releases them.
- The Ageless: All other races age, including Gods. Dragons are immortal unless they're killed. Specifically they stop aging once they reach maturity.
- Berserk Button: Destroy their treasure and they will hunt you down.
- Chaotic Neutral: Invoked. According to Ddraig, in the past, most dragons just lived freely to their hearts content. These days, it depends on the dragon. The dragon race as a whole ignored the Great War between the Three Factions (though select individuals did pick a side.
- Dragon Hoard: Some of them are known to collect treasure. Fafnir requires his contractor to give him something for his help (which, in Asia's case, is often lingerie), and Tiamat's briefly mentioned hatred of Ddraig is later revealed to be the result of Ddraig losing some treasure that he borrowed from her to fight Albion.
- Kryptonite Factor: The only things that can kill dragons are dragon-slaying weapons like Issei's Ascalon or the blood and attacks of the fallen angel Samael.
- Our Dragons Are Different: The most powerful race in the story are dragons themselves. Both Western and Eastern dragons appear, but the majority who are relevant to the story are Western.
- Unstoppable Rage: With enough provocation, a Dragon will enter "Outrage" mode, becoming significantly more powerful and vicious. Azazel commented that most people know better than to piss one off.
Dragons based from the Arthurian legend of Merlin watching an endless colossal fight between a red and white dragon (who symbolises Wales and England, respectively).
- Forever War: Ddraig and Albion have basically forgotten what the fight was originally about. Volume 21 implies it was Ddraig's flames and Albion's poison being ineffective on each other that started it, as it gave them each a Worthy Opponent for the first time in their lives, convincing them to both get stronger by constantly challenging and fighting each other.
- Inelegant Blubbering: Ddraig and Albion are completely humiliated by the former's perverted host earning the title "Breast Dragon Emperor", and are prone to uncontrollable sobbing when the topic is brought up. It didn't help when Odin labelled Albion "Butt Dragon Emperor" because Vali half-heartedly said that women's hiplines look nice when pressed for his fetish.
- Laser-Guided Amnesia: The Biblical God sealed off their memories of any abilities they had other than Boost and Divide. Once they put aside their animosity for good (which is implied to have been God's intent) over their shared struggles with breasts and butts, they begin recovering their previous abilities.
- Sealed Evil in a Can: Their intrusion in the Great War provoked the Three Factions forming an Enemy Mine, ending with their bodies getting cut up and their souls sealed into Sacred Gears. Transitioned into Sealed Good in a Can as they calmed down over the years and now look back in shame at their earlier rampages.
Welsh Dragon Y Ddraig Goch
"BOOST!"One of the two Heavenly Dragons who got sealed thanks to them fighting off the other three factions. He is the dragon who is residing with Issei as the Longinus "Boosted Gear", and thus he has to put up with all of Issei's perverted antics.
- Bilingual Bonus: Ddraig is part of a Welsh phrase meaning "The Red Dragon".
- But Now I Must Go: Tells Issei that he's losing consciousness because of him using up his powers in trying to maintain Issei's soul while Great Red and Ophis are creating his new body. Issei then sheds a lot of tears till he hears Ddraig snoring.
- Cassandra Truth: He did hear the voice of the Breast Fairy when Issei accidentally summoned it instead of being able to talk to Akeno's breasts with Bilingual. Everyone just thinks Ddraig lost it.
- Cosmic Plaything: Doesn't appreciate it when he gets called Oppai Dragon by both Ophis and Great Red.
- Cry Cute: Usually Played for Laughs regarding his humiliation over current host's obsession with breasts and the resulting title of "Breast Dragon Emperor". Played for Drama when Issei dies, and Ophis sounds somewhat surprised to hear him crying.
- Embarrassing Nickname: Oppai Dragon (Breast Dragon) and the Breast Dragon Emperor.
- Intergenerational Friendship: Considers Issei to be a true friend seeing as his former hosts never really talked much with him.
- Large Ham: Not fully, but he does put a lot of energy into his battle phrases, such as 'Boost!'
- Lonely at the Top: Was this until he met Albion. If he had never met him, he would have been only famous for his god consuming flames and wouldn't have developed his Boost and Penetrate abilities.
- Meaningful Name: Ddraig is part of the Welsh phrase Y Ddraig Goch, meaning "The Red Dragon". It also appears on the flag of Wales.
- Mood Dissonance: Tells Issei that it was fun being with him and it actually looks like he's about to say his last words to his partner. Issei couldn't even control his tears at his closest partner disappearing from him until Issei hears Ddraig snoring.
- Playing with Fire: Blazing Inferno of Scorching Flames, Ddraig's ultimate finishing move. These flames can burn anything, and once ignited, will not extinguish until ash is all that remains. Even Gods will be burnt to ashes within the flames. It is only ineffective against Albion, Ophis and Great Red.
- Pre Ass Kicking One Liner: In the dub, Ddraig's warning to Shalba becomes this:Ddraig: You made a poor decision, and now you must pay!
- Red Baron: Known as the Welsh Dragon and the Red Dragon Emperor.
- The Rival: Him and Albion have been going at it for centuries.
- Tempting Fate: When Issei reachs Balance Breaker with poking Rias' breast, he exasperatedly comments that he is going to cry if Issei keeps powering up this way. Guess what happened?
- Undying Loyalty: When Euclid Lucifuge offered him a more powerful host by joining him, Ddraig quickly rejected his offer, saying that he wants to remain with Issei despite gaining the Oppai Dragon nickname and being the weakest of his past hosts, because he's a better host than all the others.
- Vitriolic Best Buds: He hates his partner's obsession with breasts, but otherwise enjoys his time with Issei because no other host has talked to him as much, generally just focusing on power.
Vanishing Dragon Albion Gwiber
Voiced by: Ryota Takeuchi (Japanese) and Mark Fickert (English)One of the two Heavenly Dragons who got sealed thanks to them fighting off the other three factions. He is the dragon who is residing with Vali in the form of the Longinus "Divine Dividing".
- Cry Cute: He's quite upset that his rival has become associated with breasts, and Odin attempting to associate him with butts after Vali's half-hearted admission to liking hips didn't help his ego in the slightest.
- Embarrassing Nickname: Odin calls him the Butt Dragon Emperor after Vali reveals his fetish for women's butts in Volume 7.
- In-Series Nickname: Ddraig calls him the "White guy".
- Lonely at the Top: Was this until he met Ddraig. If he had never met him, he would have been only famous for his poison and wouldn't have developed his Divide and Reflect abilities.
- Meaningful Name: His name is the ancient Greek name for Great Britain. The word was used also by some Romans (instead of the official Britannia) and so it's sometimes confused as a derivation of "albus", that means "white". Also, "Gwiber" means "Serpent" in Welsh, denoting his serpent-like original form.
- Not So Stoic: His heart disease, as how they put it, get's so bad that Albion gets hysterical and hyperventilates at the mere mention of breast.
- Poisonous Person: Long ago, he was feared for his venom, which could reduce any organic matter. It was only ineffective on Great Red and the infinite Ophis, as well his eventual rival Ddraig, which motivated him to stop using it and train his body.
- Power Gives You Wings: What his Sacred Gear form, Divine Dividing, looks like.
- Red Baron: Known as the Vanishing Dragon and the White Dragon Emperor.
- The Rival: Him and Ddraig have been going at it for centuries, to the point where the two have basically forgotten what the fight was originally about.
- The Stoic: As Ddraig's opposite, his tone generally doesn't change all that much, no matter what ('Divide!' included) - even his This Cannot Be! reaction to Issei incorporating his power in addition to Ddraig's wasn't too different.
Blaze Meteor Dragon Tannin
Voiced by: Tarou Yamaguchi (Japanese) and Matt Thurston (English)One of the former Dragon Kings from Middle-Eastern/Jewish mythology. He turned himself into a devil to get a piece of land in the underworld for his fellow dragon-kind to live in. He's also one of Issei's mentors in fighting. One of the few reborn devils to reach Ultimate Class, he is Issei's inspiration. Has been Top 10 in the Rating Game for decades.
- Authority Equals Asskicking: He's capable of kicking ass and is one of the Dragon Kings.
- Badass Teacher: The Occult Club couldn't even't dent him while he used less than a thousandth of his power, and he later runs Issei through a harsh training regimen that allows him to activate his Sacred Gear at will.
- Chess Motifs: Since he participates in the Rating Games, of course he'd be assigned to one. It is revealed in Volume 14 that he is Mephisto Pheles' Queen.
- Fun Size: Can shrink himself down to Rassei's size whenever the situation calls for it.
- Informed Ability: His dragon breath is equivalent to a comet crashing down on Earth. It's also used as a measuring stick for the Villain of the Week.
- Jaw Drop: Makes an epic one when Issei asks him as to what mythology is the Breast God from.
- Mentor Archetype: Azazel asks him to personally train Issei.
- Number Two: He serves as Mephisto Pheles' Queen.
- Opt Out: He leaves the Dragon Kings to become one of the Devils to get a piece of land in the underworld for his dragon-kind to live in.
- Purple Is Powerful: In the anime.
- Red Baron: Known as the Blaze Meteor Dragon.
- Screw This, I'm Outta Here!: He ditches the Dragon Kings to side with the Devils.
Prison Dragon Vritra
Voiced by: Toshiki Iwasawa (Japanese)The evil black dragon from the Asura faction of Hindu mythology who, after being vanquished by Indra, had his soul split into pieces. One of them is Saji's Sacred Gear.
- Bystander Syndrome: If it doesn't involve him, he doesn't usually bother to get involved.
- Dark Is Not Evil: He is revealed to be an Evil Dragon, who are generally known for being Ax-Crazy, yet Vritra is on the heroes' side.
- Technicolor Fire: He is famous for his black flames, which are extremely difficult to dispel and inflict curses on whoever they burn.
- Red Baron: Prison Dragon.
- Weak, but Skilled: Considered as the weakest of the five Dragon Kings, but has a wide array of skills to make up for it.
Chaos Karma Dragon TiamatA dragon based from the primordial water goddess of Babylonian mythology. The strongest of the Dragon Kings as well as the only female among them. According to Ddraig, she hates him.
- Color Motif: Tiamat is a blue-scaled dragon with a blue magic circle and a blue-haired human form who wears blue clothing.
- Red Baron: Chaos Karma Dragon.
- The Smurfette Principle: The only female Dragon King.
- Voluntary Shapeshifting: She can transform into a beautiful woman with blue hair at will (which is consistent with the original myths where Tiamat is mostly described as a woman).
- You Can Run, but You Can't Hide: She has been chasing after Ddraig for a long time to reclaim her stolen treasure.
- You Gotta Have Blue Hair: In her human form, which corresponds to her dragon form's blue scales.
Gigantis Dragon Fafnir
A dragon from the Siegfried saga of Norse Mythology and one of the five Dragon Kings in the story, he's sealed inside Azazel's artificial Sacred Gear, Down Fall Dragon Spear.
- Authority Equals Asskicking: He's one of the Dragon Kings and can still hold his own against Rizevim.
- Batman Gambit: Despite getting beaten up by Rizevim, he still managed to curse the guy enough that he would be tormented by nightmares. This manages to make Rizevim impatient thanks to lack of sleep.
- Beware the Silly Ones: He was given to Asia to protect her from enemies trying to Shoot the Medic First, but each of his appearances simply serves to humiliate her by demanding her lingerie... until Rizevim hits Asia, whereupon he enters an Unstoppable Rage that doesn't end until he delivers the fatal blow on Rizevim.
- Big Damn Heroes: He lands the finishing blow on Rizevim at the end of the latter's battle in volume 20.
- Dirty Old Man: Considering the other dragons aren't even perverted in nature, he stands out.
- The Ghost: He makes his actual appearance in Volume 14.
- Gold-Colored Superiority: He's gold colored and is one of the Dragon Kings.
- Kick the Son of a Bitch: He's responsible for the death of a ruthless devil who planned to revive Trihexa.
- Power at a Price: To even have a pact with him, he just wants a treasure. Azazel had it easy because Fafnir just wanted a rare treasure. For Asia though, it's her treasured underwear.
- Red Baron: Gigantis Dragon and Golden Dragon Monarch.
- Unwitting Instigator of Doom: His killing of Rizevim ends up causing Trihexa to be unsealed.
Sleeping Dragon Midgardsormr
Also known as Jormungand. One of the five Dragon Kings, he's a son of Loki and is currently sleeping at the ocean near Scandinavia. He's also the laziest dragon.
- Bystander Syndrome: Doesn't care much for things unless it's time for Ragnarok.
- Crouching Moron, Hidden Badass: In the original myth, his designated enemy is Thor, who is included in the Top 10 strongest in the series. You will not believe it at first because he is such a Lazy Bum.
- The Giant: Even by dragon standards. Midgardsormr is even larger than Great Red despite being far less powerful than the latter.
- Lazy Bum: Like you would not believe.
- Heavy Sleeper: Sleeps at the bottom of the ocean near Scandanavia.
- Red Baron: Sleeping Dragon and Dragon of the End.
- Slept Through the Apocalypse: Inverted - he's sleeping until the apocalypse.
Mischievous Dragon Yu-Long
Voiced by: Yuki Arai (Japanese)The youngest of the five Dragon Kings in the story, he also accompanies the original Sun Wukong whenever the latter gets sent by Indra to somewhere. Also featured in Journey to the West.
Dragon God and True Dragon
Ouroboros Dragon Ophis
- I, went under for thirty minutes.Voiced by: Suzuko Mimori (Japanese) and Megan Shipman (English)
- Absolute Cleavage: Her dress exposes so much of her chest that even her nipples would be completely exposed if they weren't instead covered by tape.
- All-Powerful Bystander: Even after losing much of her power, she's still twice as strong as the Heavenly Dragons combined, but remains hidden in Issei's house because the world at large still views her as a terrorist leader.
- Animal Eyes: Her eyes have reptilian, slitted pupils.
- Authority Equals Asskicking: She's the initial leader of the Khaos Brigade, the strongest dragon of the dragon race and is one of the most powerful characters in the series.
- Batman Gambit: When Samael drained her powers, she actually sent out snakes that contained her power, which helped her avoid losing 75% of her powers.
- Because You Were Nice to Me: Ophis initially cared about nothing except removing Great Red from the Dimensional Gap. This changes when the Occult Research Club get over her being a terrorist leader. She once protected Asia and Irina from an attack simply because the former served her tea and the latter played cards with her. After being rescued from Shalba by Issei, who suffers a lethal dose of Samael's poison in the process, she helps create a new body for him and starts living at his house. Back when she led the Khaos Brigade, Vali was the only person who regularly tried to socialize with her, for which she expresses gratitude while giving him his own version of Diabolos Dragon to defeat Azi Dahaka.
- Breast Expansion: Gets this in her older form.
- Brutal Honesty: Uses this to describe the Occult Research Club to a staff of the department store so she can page them throughout the entire store.
- Cheerful Child: Thanks to Issei's exceptionally good parental skills, not to mention the efforts of Akeno and Rias (both of whom she recognizes as "momma"), she begins acting like a very happy and healthy little girl, to the delight of the whole harem and Issei's own parents.
- Cherry Tapping: When Issei wakes up in his spirit form, he sees Ophis tapping the ground. When asked, all she said was "I'm defeating Great Red here." Yes, it's a mix of funny and adorable.
- The Comically Serious: "Did you want to become the Oppai Dragon instead of the Heavenly Dragon Ddraig?" which sends Ddraig into his Heroic B.S.O.D..
- Hell, anytime she's on-screen, it will be a mix of both hilarious and adorable.
- Dark Is Not Evil: At least Issei thinks so.
- Did We Just Have Tea with Cthulhu?: Hangs out at Issei's place in Volume 11.
- Elegant Gothic Lolita: Its current form since according to Azazel, last time Ophis appeared was in the form of an old man.
- Foreshadowing: The dream Issei had when Ddraig made his first appearance was his marriage to Rias with his mother crying out "make sure your first child is a girl!" Ophis is currently taking on the form of a little girl, and she's the daughter of Issei and Rias (and Akeno since Ophis calls her and Rias momma), by adoption, with Issei having no prior children.
- Happily Adopted: For all intents and purposes. She quite often acts as Issei's child, and actively calls him "Papa." She also recognizes both Rias and Akeno as "Momma" to both of their delight.
- Has Two Mommies: She calls both Rias and Akeno "Momma."
- Immortal Immaturity: Probably because she didn't have friends for thousands of years.
- Intergenerational Friendship: With Issei.
- The Load: Volume 11 is pretty much her not being able to do anything at all and is a burden to the entire group. This is actually justified, as losing some of her power made her remaining abilities unstable. When she attacked the Grim Reapers, she accidentally blew up Azazel. Also, she is effectively invincible, so she doesn't really understand the necessity of self-defense.
- Magic Enhancement: Ophis can create snakes which massively boost the power of those who consume them.
- Moment Killer: Dammit Ophis! Just when Issei and Ravel were having a good time at the bath.
- Mystical Waif: The leader of a terrorist organization and one of the strongest characters in the series currently appears as a little girl, though Azazel notes that she used to take the form of an old man.
- Nerf: Somewhat over 1/4 of her power is drained from her, lowering her from being the strongest known being alongside Great Red to being "only" twice as strong as Ddraig and Albion combined at their primes (and this while her powers were still unstable).
- Nigh Invulnerable: Pre-Nerf, virtually nothing works on her. She gets stabbed by Cao Cao using True Longinus, and she doesn't even flinch as the entry wound simply closes without losing a drop of blood. However, even she isn't immune to Samuel's curse, which causes the aforementioned nerf.
- No Biological Sex: Despite choosing to appear as female, Ophis is genderless, as revealed in her side story.
- No-Sell: Does this to Cao Cao and the freaking True Longinus.
- Older Alter Ego: Gains an older form in Volume 21.]]
- Only Known by Their Nickname: Ophis is known by "Phis" to those outside the Hyoudou Household to avoid people realizing who she is and since Lilith is believed to be Ophis prior to her Heel–Face Turn. This is seen best with Kunou who even after moving into the Hyoudou Household, still doesn't know her real identity.
- Ouroboros: Represents infinity, and its powers are manifested in the form of snakes.
- Pointed Ears: Its current form has ears with pointed tips.
- Puppet King: S/he is considered as the overall leader of Khaos Brigade, but the ones below her are the ones who are truly running the group.
- Quizzical Tilt: She has a habit of doing this whenever she's thinking about something.
- Rapunzel Hair: Its current form has long black hair down to her hips.
- Red Baron: The Infinite One and the Infinite Dragon God.
- Redemption Demotion: As soon as she finally joined Issei's group, almost all of her power was drained (most of it swallowed by Samael, and then had to create Issei's body alongside Great Red).
- The Rival: To Great Red.
- Stephen Ulysses Perhero: Ophis is the Greek word for "Snake", referring to her abilities
- The Stoic: Rarely shows any sort of emotion.
- Story-Breaker Power: Even if she got hit with the Nerf stick, she's still twice as strong as Prime!Ddraig and Prime!Albion combined, which is why she's not out fighting alongside the members of the Occult Research Club.
- Super Empowering: She gives both Issei and Vali the Diabolos Dragon armor, which allows them to defeat opponents as strong as their own Heavenly Dragons, but not without severe backlash.
- Sweet Tooth: Ophis loves eating sweets. This trait was also passed down to Lilith her clone.
- Trademark Favorite Food: She often snacks on bananas while living in Issei's house.
- Voluntary Shapeshifting: S/he's capable of shifting from one form to another. As noted by Azazel, form for Ophis is just simply a decoration.
- The Worf Effect: For someone to be the Infinite One, she sure loves to be a Distressed Damsel seeing as she got captured by both Samael and Shalba. Justified because she only has one thing in mind: kick Great Red out of the Dimensional Gap.
- Worf Had the Flu: She is beaten to a pulp by one of the Evil Dragons of Qlippoth. Aside from her getting nerfed, this happens because said dragon was using Issei's parents as shields, and kept threataning the dragon egg she was tasked with guarding so she could not run away.
- World's Strongest Man: Pre-Nerf she was this taking the top spot of the Top 10 Strongest Beings in the World.
Apocalypse Dragon Great Red
The only one who can rival Ophis and is currently residing in the Dimensional Gap. Ophis' wish is to kick him out of there while Vali wishes he could fight him. He also represents dreams.
- All-Powerful Bystander: Is the single strongest known being in existence alongside Pre-Nerf Ophis, but just swims in the dimensional gap without bothering anyone, and the various gods, demons, and other factions likewise leave it alone. Word of God excludes him from the Top 10 Strongest Beings in the World for this reason.
- A Taste of Power: From Issei's perspective. Issei was shocked in awe as to how powerful Great Red really is.
- Delinquent: How Issei describes him as: a biker gang dude who hates being stared at.
- Disproportionate Retribution: When a monster glared at him, he tells Ddraig that he'll combine with him and wipe out all the huge monsters.
- Dynamic Entry: How he enters the underworld with Issei and Ophis at his back. While inadvertently, to the tune of the Gropin' Dragon. Guy knows how to make an entrance.
- Fusion Dance: With Issei after the latter's revival, turning him into a giant to defeat Jabberwocky.
- Kaiju: Great Red is positively colossal.
- Red Baron: Known as the True Dragon, The True Red Dragon God Emperor, and "D x D" (Dragon of Dragons).
- Satan: Not in-story, but he represents the Great Red Dragon that Satan became in the Book of Revelation.
- Story-Breaker Power: It's a good thing he doesn't fight actively and chills around at the Dimensional Gap, otherwise the whole story would have been over.
- Suddenly Voiced: While Issei is getting his body reconstructed with Great Red's flesh, anything he wants to say is conveyed by Ddraig. After helping Issei destroy the Jabberwocky and save the Underworld, what are the first words that come directly from his mouth? The Oppai Dragon song!
- The Rival: To Ophis.
- Title Drop: It's known as "D x D" or Dragon of Dragons.
- Ax-Crazy: They were feared for wanting to destroy everything, including themselves. Even Ddraig and Albion decided against confronting them, despite being much more powerful than the strongest three in the past. Grendel and Azi Dahaka fought against each other just to figure out who's going up against the Vali team.
- Back from the Dead: With the exception of Crom Cruach, who never died in the first place, and possibly Níðhöggr (Rossweisse explicitly notes that they're not sure if he revived on his own or not), they were all revived by the Sephiroth Graal, with their vulnerability to Dragon Slayers slightly mitigated, to serve Qlippoth.
- Dark Is Evil: All of them except Ladon are described as having black scales.
- Resurrective Immortality: Volume 21 implies that as long as even a small piece of an Evil Dragon's soul remains, they can revive themselves, though it takes a few thousand years. Azi Dahaka and Apophis both hope to have a rematch with Vali and Issei, respectively.
Crescent Circle Dragon: Crom CruachThe strongest known Evil Dragon that is based on an old god in Irish Mythology. He makes his first appearance in Volume 16 in a human disguise, but is forced to partially reveal his dragon form in a battle against Issei and Vali.
- Big Damn Heroes: In Volume 20, he rescues Issei's parents from Níðhǫggr and kills him.
- Break the Badass: This guy can make Grendel back down from a fight.
- Comically Missing the Point: He seriously has no idea why Fafnir would want Asia's school swimsuit. He even thought that Fafnir was going to swim.
- Even Evil Has Standards: He is disgusted by most of Qlippoth's actions, but what really tips the scales is how one of his fellow evil dragons tormented Ophis. He breaks out his true form on the culprit, Níðhǫggr, and contniuously beats him down, presumably force feeding him his horde of synthetic Phoenix Tears until they run out, just to prolong the suffering, and use up the supply so Qlippoth won't have access to them.
- Heel–Face Turn: He ends his partnership with the Khaos Brigade after the battle against Heaven in Volume 18.
- Last of His Kind: As of the end of volume 21, Crom Cruach seems to the the only evil dragon left.
- Mark of the Supernatural: In his human form he has a mixture of black and blonde hair with matching black and gold eyes.
- Meaningful Name: His title is actually the meaning of his name, and in the original myths he is suggested to be a solar deity.
- Noble Demon: While he does enjoy fighting strong opponents, he has much more self-control than the other Evil Dragons.
- One-Winged Angel: Of the "behold my true form" variety. He appears as a human when he's first introduced, but he reveals his true dragon form to Níðhǫggr in volume 20.
- Paper-Thin Disguise: His cover as "Mr. Black", a temporary replacement Pawn within Rias' team. It is just him taking his human form with a different set of clothing (black, in this case).
- Red Baron: Crescent Circle Dragon, Darkness Dragon and Dark Dragon of the Crescent Moon.
- Rule of Three: With Ddraig and Albion, Crom Cruach is the third dragon from the British Isles, and they are considered the strongest of their kind (excluding Ophis and Great Red)
- Scaled Up: He turns into his true gigantic dragon form during his battle with Níðhǫggr.
- Sole Survivor: Barring the mass-produced Evil Dragons that decided to serve Asia, he is the only Evil Dragon who's alive and well by the end of the fourth arc; the rest were sealed or simply killed (though they're implied to have Resurrective Immortality).
- Super Toughness: He can tank Issei's Ascalon boosted Crimson Blaster attack with only minimal damage. What makes this so remarkable is that unlike Grendel he has never been modified to be immune to Dragon Slayers.
- Took a Level in Badass: He's stated to have been training his body and mind in both the Human World and the Underworld for the time that Ddraig and Albion have been sealed. When Ddraig finally meets him again he states that he may have even attained strength to that of the Heavenly Dragons. By the final arc, he's surpassed them.
- Voluntary Shapeshifting:
- He has the ability to shapeshift from his dragon form to his human form at will, and claims that his human form doesn't noticeably reduce his power compared to his dragon form.
- He then reveals his true dragon form in Volume 20 before a frightened Níðhǫggr.
- Weaksauce Weakness: Subverted. He originally could be critically injured by using Tathlum, the magical bullets that killed Balor, but his training makes him capable of defending against it.
Crime Force Dragon: GrendelAn evil dragon that is based on the antagonists seen from the tale of Beowulf. Like the actual story its based on, Grendel had actually been killed by Beowulf in this universe's history, and first appears in Volume 14 for a one-on-one duel against Issei.
- Blood Knight: Really loves fighting.
- Breath Weapon: He can breathe fire.
- Combat Sadomasochist: Akeno's got nothing on him. The protagonists are particularly disturbed when getting his eye gouged out, and then most of his body getting vaporized, only excites him further.
- Composite Character: In a meta-sense. He is described as having the combination of the torso of the original Grendel with limbs and wings of the dragon that Beowulf defeated after killing the giant.
- I Lied: He told Issei that it was going to be a duel between the two of them. Then he shot out three fireballs at the other team. Issei calls him out, which he claims that he really wants to kill someone just to satisfy himself.
- Let's Fight Like Gentlemen: Invoked and subverted. See I Lied trope above.
- Lightning Bruiser: Even if he's a tall dragon, he moves pretty quick. Even a CCD equipped Issei is having a hard time against him.
- Red Baron: Crime Force Dragon and Berserker Dragon of Great Sin.
- Sealed Evil in a Can: In Volume 17, Grendel is the first Evil Dragon to suffer defeat due to the solution team DxD came up with to stop the dragon's reincarnation. Upon physical defeat, Koneko uses her powers to seal Grendel's soul in one of the detachable jewels on Issei's Sacred armor. The jewel with Grendel's soul was then given to Heaven to safeguard behind a multitude of defensive barriers.
- Super Toughness: Even for a Dragon he's known to be able to tank insane amounts of damage, so much so that Rossweisse suspects that his defense has been further enhanced since his resurrection. He's been shown shrug off attacks from Xenovia's Ex-Durandal, an Ascalon boosted CCD Issei, and even Kiba's Demonic Emperor Gram.
- Too Kinky to Torture: He loves pain.
- Villainous Breakdown: He's initially elated by Sairaorg's strength and determination, but the latter's refusal to go down no matter how badly injured he gots soon frustrates and even terrifies him.
Insomniac Dragon: LadonAn evil dragon based on its serpent counterpart that guarded the Golden Apples of a special Hesperides tree in Greek Mythology. He makes his first appearance in Volume 17 during the raid on Hell's Agares Territory.
- Barrier Warrior: Very much so. Ladon can force up powerful barriers to not only defend himself, but trap people in barrier bubbles. He can also multi-layer the barriers in-case the first one gets destroyed.
- Red Baron: Insomniac Dragon.
- Sealed Evil in a Can: In Volume 18, Ladon is the second Evil Dragon to be defeated through the sealing method that captured Grendel.
- Super Toughness: Like the rest of the Evil Dragons, he can take a lot of punishment before getting a single scratch. Even more so considering his barrier abilities.
- When Trees Attack: His physical body is stated to have a tree-like appearance in the form of a dragon.
Abyss Rage Dragon: NíðhǫggrAn evil dragon based on its counterpart that gnawed on the world tree of Yggdrasil in Norse Mythology. He plays a large role in Volume 20 starting from the attack on Issei's house.
- Big Eater: True to his origins, he eats everything he can get his mouth on. In particular he really interested in tasting the Spectre Dragon egg that the [DxD] was safe-guarding.
- Dirty Coward: Delivered a truly horrific No-Holds-Barred Beatdown on Ophis. How? He used Issei's parents as human shields so Ophis couldn't fight back, and kept threatening the egg so Ophis could not run away. When he saw Crom Crauch, who was also guarding the egg appear, he panicked and ran away.]
- Hate Sink: He kidnaps Issei's parents, uses them as hostages to beat the crap out of Ophis, and then fantasizes about how good the former couple will taste in front of their son while fondly reminiscing over his beatdown on the latter. His actions are so abhorrent and cowardly that fellow Evil Dragon Crom Cruach turns on him.
- Power Of Hate: The legend is that he's so full of hate and resentment that he would even resurrect himself after Ragnarok, which is supposedly the end of all things.
- Red Baron: Abyss Rage Dragon and Extrajudicial Death Dragon.
- Resurrective Immortality: It's not clear whether he's alive to serve Qlippoth because of the Holy Grail or just his natural ability to revive himself with his undying malice.
- Screw This, I'm Outta Here!: Subverted. He decides to bail out after Crom Cruach corners him, but he doesn't get that far as he's killed in the process.
Diabolism Thousand Dragon: Azi DahakaAn evil dragon from the Persian mythology and the son of Angra Mainyu, who is considered to be the archetypal evil in the Zoroastrian faith, similar to Lucifer. He first appears in Volume 17 by assisting Qlippoth during the raid at the Agares territory.
- The Archmage: Said to have control over a thousand magics. It's not clear whether that means a thousand different spells or a thousand different styles of magic, but his power is appropriately feared by the Gremory and Sitri groups.
- Big Bad Duumvirate: With Apophis after Rizevim is killed.
- Blood Knight: What he wants most is to fight and defeat strong foes, and he'll do any and every despicable thing he can to make it happen.
- Came Back Strong: Invoked. Every time he's defeated and resurrects he grows stronger.
- Lightning Bruiser: Considered by Kuroka as the strongest enemy they've fought. Given they already fought a god with his wolves that can kill a god alongside the Gremory team and Tannin included, the scale just went off the charts.
- Lotus-Eater Machine: Traps Vali in one in volume 21, giving him the experience of an ordinary loving family like Issei's. When Vali works up the willpower to leave, Azi Dahaka praises him and apologizes for resorting to such tactics.
- Multiple Head Case: He has three heads. Each one is sentient and has its own thoughts, though they are always of the same opinion.
- Red Baron: Diabolism Thousand Dragon and Forbidden Dragon of Demonic Origin.
- Took a Level in Badass: By volume 21, he is noted to have reached Heavenly Dragon level like Crom Cruach.
- Worthy Opponent: It sees Vali and Albion as this in volume 21.
Eclipse Dragon: ApophisAn evil dragon from the Egyptian mythology. Also known as Apep, the Light Eater and arch-enemy of Ra (or Aten).
- Affably Evil: He has a refined and sophisticated personality and is nothing but polite during his fight with Issei. This doesn't stop him from using Trihexa to attack multiple mythologies and the human world.
- Ambiguously Brown: Subverted. His human form has brown skin, but he comes from the Egyptian mythology. Thus, it makes sense that he would take after Egyptians.
- Big Bad Duumvirate: With Azi Dahaka after Rizevim is killed.
- Blood Knight: He loves battles and fighting, though he's less outwardly vicious than most Evil Dragons.
- Casting a Shadow: Uses shadow attacks that have a Touch of Death ability.
- Even Evil Has Standards: He heavily dislikes the sort of barbarism displayed by Evil Dragons such as Grendel and Niðhöggr.
- Kaiju: His true form is over 100 meters long, making him second only to Midgardsormr as the largest known dragon.
- Making a Splash: Uses "Black Water" to submerge his surroundings and attack his opponents.
- Red Baron: Eclipse Dragon and Primal Eclipse Dragon.
- Took a Level in Badass: By volume 21, he is noted to have reached Heavenly Dragon level like Crom Cruach.
- Voluntary Shapeshifting: Can transform into a handsome young man.
- Villainous Valor: Despite doing a great many nasty things, and trashing the realms of many, many mythologies, he gives Issei a fair fight and the space the latter needed to unleash his most powerful attacks.
- Worthy Opponent: Sees Issei as one.
Venom Blood Dragon: Yamata-no-OrochiA Japanese evil dragon who was already killed by the god Susanoo.
- Breath Weapon: Each head can spew fire from its mouths.
- Flat Character: Nothing is known about its personality, though this is justified by the fact its soul is split in half and never seen in its complete form.
- Irony: Half of its soul was sealed into the Kusanagi Sword which was found in its corpse.
- Orochi: The dragon of Japanese legend killed by the storm god Susanoo.
- Red Baron: Venom Blood Dragon and Ethereal Devouring Mad Dragon.
- Poisonous Person: Its fangs contain a deadly lethal poison that can even taint a victims soul.
- Tears of Blood: Described with having tears of blood running from its eyes.
A sprite dragon who is Asia's Familiar.
- Does Not Like Men: His introductory story has him zapping any male in his vicinity.
- Familiar: Asia's Familiar.
- Meaningful Name: His name is a combination of "rai" (lightning) and "Issei".
- Ridiculously Cute Critter: One of the first things Asia notes about him is how cute he is.
- Shock and Awe: As a sprite dragon he can use lightning.
- Yellow Lightning, Blue Lightning: The lightning he uses is blue.
Anselmus, Cyril, Gregorios, and SimeonFour mass-produced Evil dragons Asia made pacts with.
- Flat Character: Nothing is known about their personalities, and their only dialogue has been some variant of "yes".
- Heel–Face Turn: Made pacts with Asia because of Fafnir's cooking show.