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According to director Hidetaka Miyazaki, the Crystal Ring Shield's "attack" is supposed to be based off of Ultraman's Ultra Slash attack from the Japanese television show of the same name. However, he has stated he was not entirely happy with how it turned out, as the artist he was explaining it to did not quite understand what he meant when trying to explain how it would look "like Ultraman".
Contributed by G-Haven
There was originally a levelling system that allowed players to sacrifice their stats to restore their humanity. Each stat reduction would give the player four soft-Humanities each, with the limit being the base stats the player started the game with. The actual soul-level of the player does not reduce, possibly due to the system not being complete. However, the player could increase their stats without their soul-level increasing, up to the point of how many stat-levels they sacrificed. This would have made it a functional "Respec System", which would have allowed players to Reallocate their stats, albeit slowly.
Contributed by G-Haven
Amongst all the hollow-corpses strewn across the game, there are only ten female hollow-corpses to be found. Nine of the ten bodies each refer to specific characters, some of them being summonable White Phantoms, four of them being Fire Keepers, and only one unknown female who is found holding Twin Humanities on their body in the Lower Undead Burg.
Contributed by G-Haven
In the Artorias of the Abyss DLC, there is an NPC named "Marvelous Chester" in The Royal Woods. Like the chosen undead, Chester was pulled from his time period by Manus. Chester vaguely describes his era as Gothic/Victorian, his clothing also appears to be attire from the 19th century.

The character may have been included as a small hint as to what was coming up in Bloodborne.
Contributed by DrakeVagabond
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The Crystal Lizard model from the previous From Software game Demon's Souls can be found within the game's files. It was likely used as a placeholder until a new model was made specifically for Dark Souls.
Contributed by G-Haven
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In an interview with the design team, the first draft for Kirk's Thorn Armor was going to be based off Hydra from the manga Saint Seiya: Knights of the Zodiac. Art designer Daisuke Satake and director Hidetaka Miyazaki didn't see eye to eye with the initial concept, as Satake's concept was "a huge guy covered in spikes", so they reworked it.

The final design began to take shape when Satake and Miyazaki began to talk about the Trial of 77 Rings from the manga JoJo's Bizarre Adventure, in which two characters had to earn their knighthood by defeating other combatants and wearing the rings they had on them onto their body, collecting a total of 77 of them. Miyazaki and Satake both liked the concept and decided to see what it would look like if the rings also had thorns on them.
Contributed by G-Haven
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Andre of Astora originally had a much different role in the early development stages of the game. He was originally going to be the son of Gywn and would also guard a door within the Fire Link Shrine, which he would physically move the goddess statue blocking it at some point in the game for the player. As development went on, his role was changed to that of a blacksmith.
His previous role as a guard of a door wasn't completely scrapped however, as he does hold the Crest of Artorias, which is needed to unlock the door to Darkroot Garden.
Contributed by G-Haven
Knight Artorias (aka Artorias the Abysswalker) has cut dialogue found in the Artorias of the Abyss DLC. The cut dialogue implies he is not actually human himself and was slowly losing control over his own body and mind to the corruption of the Abyss, telling the player to stay away for their own good. In the final version of the game Spoiler:Artorias had already been completely overwhelmed by the Abyss, having no dialogue whatsoever.
Contributed by G-Haven
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The Brass Armor set which is worn by the Darkmoon Knightess was originally a starter-set for a class that was described as a "Pagan Knight." However, there was trouble with balancing it, so it was ultimately given to the Darkmoon Knightess found later in the game.
Contributed by G-Haven
Using the Wrath of God and Force miracles, it is possible to deflect projectile spells and arrows if timed correctly. This can also be applied to deflect the bombs thrown by the Giant near the top of Sen's Fortress.
Contributed by G-Haven
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The Possessed Trees in Darkroot Garden have an unused attack animation, using their vines to swipe down at players. The idea of the trees attacking was likely left out because the developers wanted to trick players into thinking a path was blocked by a real tree and having to figure out to cut it down themselves, instead of attacking an enemy that is actively attacking them in order to unblock a path.
Contributed by G-Haven
There are unused attack and death animations for the primordial serpents Kingseeker Frampt and Darkstalker Kaathe. At some point, they were intended to be killable but developers chose to make them immortal, likely because if Frampt Spoiler:was killed before transporting the player to the last location, the game would become unbeatable.
Contributed by G-Haven
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Crossbreed Priscilla has unused animations for standing and sitting. According to a developer interview, she was originally meant to be an ally of the player. As development went on, her initial role was eventually replaced by the Firekeepers. The unused animations were likely a remnant of her previous role, which are reminiscent of the Maiden-in-Black from Demon's Souls who was is a different location and position each time visiting her.
Contributed by G-Haven
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The spiky crystal statues that are found periodically in The Depths, the Crystal Cave and the Duke's Archives are actually the bodies of other players who had been killed by being cursed.
Contributed by G-Haven
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Three unused rings can be found within the game's data. These rings are:
• Ring of Displacement: This ring takes damage in place of its wearer, but has a fixed chance of breaking
• Ring of Blind Ghosts: It prevents its wearer's discovery by cursed ghosts.
• Ring of Condemnation: granted to those who enter a Covenant with Velka, the Goddess of Sin.
Contributed by RetroHell
Despite the two games being in separate universes/worlds, Patches the Hyena from Demon's Souls appears in Dark Souls under the same name. His role in Dark Souls is also the same as in Demon's Souls.
Contributed by G-Haven
Unused dialogue from Ingward suggests that the player was supposed to fight "a Darkwraith, a servant of the Four Kings" before obtaining the Key to the Seal.

This dialogue may refer to the Undead King Jar-Eel, a cut boss from the game, as one of King Jar-Eel's weapons is a Dark Hand, which is used frequently amongst Darkwraiths.
Contributed by ThisGuyInTheSuit
Hidetaka Miyazaki, the director of Dark Souls, said that the Pendant gift had no use in the main story, and that he had only added the item to play a joke on the players. However, whenever Miyazaki plays the game, he would either pick the Pendant or nothing as a starting gift.
Contributed by ThisGuyInTheSuit
Unused text from the game's data reveals that Shiva of the East's main goal is to obtain the Chaos Blade. If the player manages to get one, Shiva will even go as far as attacking the player to obtain it.
Contributed by ThisGuyInTheSuit
There is an unused Miracle called "Escape Death" in the game's files that acts as a Rare Ring of Sacrifice, letting the player die, but also keep all of their souls and humanity. It is likely that this was removed due to developers noting that it would remove the penalty of death, making the game unbalanced.
Contributed by ThisGuyInTheSuit
Oscar, Knight of Astora (the knight who gives the player the Estus Flask in the Undead Asylum) was likely supposed to take a more prominent role. Unused dialogue in the game's files suggests that he was supposed to help the player in Darkroot Garden, as well as engaging in a confrontation with the player at some point in the story.
Contributed by ThisGuyInTheSuit
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It is commonly speculated that Gwyndolin was a son of Lord Gwyn raised as a woman due to his affinity to the moon. Unsurprisingly this leads to him having feminine traits such as long hair, fair skin, and feminine clothing. But surprisingly he also has breasts. This is because the character model used for Gwyndolin is a female character model, despite the fact the character is actually male. This trait is also present in the Dark Souls Art Book.
Contributed by VNRob
In the Prepare to Die Edition, the player has an opportunity to save a young Sif from the Abyss. After doing so and summoning Sif for a boss fight deep in the Abyss, if the player has not yet defeated Sif in the present, the opening cutscene will change.

Sif appears to recognize the player, and is reluctant to do battle with them, but finds it necessary, likely due to Sif swearing to protect the grave or the Covenant of Artorias. This cutscene makes the hobbling animation when Sif is at low health even more heart-wrenching for some players.
Contributed by TomGuycott
The Bounding Demons in Lost Izalith are actually made from the same mesh as the lower half of the Undead Dragon minibosses. Neither of the two Undead Dragons ever stand, and the one in the Painted World Ariamis crawls forward and disconnects from its lifeless lower half. There is a glitch where attacking the lower half when you can reach it with a plunging attack will prompt the body to shoot up onto its legs like a Bounding Demon, thus eliminating the need to unlock several doors and pass through a fog gate.
Contributed by TomGuycott
New Londo, in the game's lore, is a city that was submerged in a flood of water in order to prevent the spread of the Abyss and the Darkwraithes. The city is populated by the vengeful ghosts of those who were martyred in order to prevent the spread of the Abyss. In the New Londo Ruins, the two Banshees that players can encounter are clutching what appear to be their babies to their chests.
Contributed by TomGuycott
The in-game descriptions of the Mask of the Sealer and the Remedy sorcery speak of two other Sealers aside from Ingward who abandoned their duty to watch over the Seal of New Londo. One Sealer, Yulva, is said in the Remedy description to have gone to Blighttown to cure the sick. It can be speculated the corpse where the Crimson Set, Tin Banishment Catalyst and Remedy spell, all of which would be associated with a Sealer, is her.

The second is unnamed, but there is only one other male NPC in the game who wears the complete Sealer set, sans the mask. It is worth noting that the Mask of the Sealer was a "symbol of their resolve", which he would lack had he abandoned his duty. In Anor Londo when confronting Lautrec with the Black Eye Orb, he can be seen assisting Lautrec as a White Phantom. Seeing as Phantoms exist outside of the player's true timeline, it is unclear whether or not the man remains alive in the game's present.
Contributed by TomGuycott
The Ceaseless Discharge, who is revealed to be the only son of the Witch of Izalith by the in-game description of the Orange Charred Ring, can be instantly killed if provoked into attacking the player after they remove the Gold Hemmed set from the altar near him. Provoking him into attacking the player there specifically and then running back to the Fog Gate makes him charge after the player and leap over the chasm below to try and stop them from escaping. The result leaves him desperately grabbing the ledge, from which point the player can attack his arm and send him falling to his death.
Contributed by TomGuycott
Despite the name, the Four Kings fight can produce more or in rare cases less than Four Kings. This is due to the nature that the boss fight itself is one health bar shared between however many kings required to empty it, with a new king spawning every minute there is less than four. Because of this spawning, if a player kills three kings and fails to kill the fourth fast enough, three more kings can eventually spawn with full health on the individual monsters, but no additional health added to the total health bar. The health also seems to increase when Phantoms are summoned to assist the player.

On the flip side, under the right conditions there can be as little as ONE king spawned that still results in victory for the player. Kings cannot INDIVIDUALLY be damaged when performing their Lifedrain grab, but attacking a king in the middle of the animation does damage to the total Kings lifebar. They are still able to be damaged during their death animation as well, and with enough players and the proper buffs, this makes killing less than four of the Kings possible.
Contributed by TomGuycott
Though ill-advised for an inexperienced player, a surprising number of boss fights are optional. Certain fights, such as the Taurus and Capra demons in the Undead Burg, can be bypassed by choosing the Thief class or choosing a Master Key as your Gift when building a character. Some are simply well-hidden, like the Stray Demon, Crossbreed Priscilla (who does not even start out hostile), and Dark Sun Gwyndolin. The Demon Firesage and Centipede Demon can be bypassed by being a high-ranked member of the Chaos Servant Covenant, and finally, perhaps the most difficult to bypass of all, the Ceaseless Discharge can be avoided by having enough vitality, healing, fire protection and speed to run across the molten lava he produces in the Demon Ruins.
Contributed by TomGuycott
Lautrec of Carim is a very obvious nod to Yurt, the Silent Chief from Demon's Souls. Both are heavily armored with their faces covered, both use twin shotels and parrying daggers, both are first found imprisoned and imploring that the player help free them, and both eventually begin to murder other NPCs. The difference is the scope of their killing; while Lautrec is limited to one murder, Yurt can murder nearly all the NPCs in the Nexus.
Contributed by TomGuycott
Even more embarrassing than the fact it can be defeated by Black Iron Tarkus without any aid from the player on an initial playthrough, it is possible to knock the Iron Golem completely off the battlefield when he loses his balance, resulting in an instant death for the boss.
Contributed by TomGuycott
Unlike the majority of characters throughout Dark Souls, Sieglinde of Catarina, the daughter of Siegmeyer, is speculated to be a human. All the human characters met in Dark Souls are either Undead, who are reborn at Bonfires at the cost of their humanity until they are completely Hollow, or are non-human in some other regard. This makes her quest to find her father all the more treacherous, given the fact that the moment she dies, she is dead for good.
Contributed by TomGuycott
Subtle references and similarities to Kentaro Miura's manga "Berserk" can be found hidden in the game. The earliest example that can be discovered is the blacksmith Rickert, the name of a character in Berserk who was also a blacksmith.

Beatrice the Witch, who can be summoned twice as a Phantom for boss fights, bears a striking resemblance to the Berserk character Schierke.

The main character of Berserk, Guts, can also be seen referenced in a few different ways. A much more subtle reference is Black Iron Tarkus, a character summoned as a Phantom and seen later as a corpse in Anor Londo. His black armor and greatsword are said to be absurdly heavy and only able to be donned by him due to his incredible strength. Guts, while his armor is somewhat differently designed, is known for wielding weapons of absurd weight, and was also known for wearing black armor. What's more, the design of the Dark Souls Greatsword resembles the design of one of Guts' earliest swords.

The second reference is contained within the Dark Souls DLC in the form of Artorias, the Abysswalker. Some similarities include the design of Artorias' armor and Guts' Berserker Armor, their swords' abilities to damage demons and ghosts, their symbolism and references to wolves, their mangled left arms and their losses of sanity (though for varying reasons). In addition to that, many of Artorias' poses both for the DLC promotions and for in-game cutscenes greatly resemble official artwork of Guts from Berserk.
Contributed by TomGuycott
The Pisaca in the dungeon in the Duke's Archives are actually humans captured by the Channelers for Seath's experiments, explaining why these creatures drop a fairly consistent supply of Humanity. Two in particular each drop a different Miracle. When considering the fact that Rhea of Thorolund's Hollow can be found in the dungeon after all her Miracles are purchased, and the fact a corpse in the dungeon is wearing the Maiden Set that Rhea wears, it can be speculated that the two docile Pisacas are former Maidens, and that Rhea was going to receive the same fate.
Contributed by TomGuycott
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Demon Souls and Dark Souls are the spiritual successor to From Software's previous hardcore action RPG series King's Field, and both contain many references to it. Particularly, Seath the Scaleless in Dark Souls is a reference to Seath the white dragon in King's Field who is normally portrayed as a force of good.

What's even more interesting is that in King's Field lore, Seath's nemesis is the evil Guyra who also appears as the final boss in several of the King's Field games. He is described in the manual of King's Field II as:
"The Black Dragon who is opposed to the White Dragon, "Seath." Guyra broke a black crystal which controls the powers of nature. He created the "Moonlight Sword" to make his chosen warriors fight for his revival."

In the King's Field II, he appears as a one-eyed dragon. Guyra's appearance is very similar to the character introduced in the Prepare to Die expansion of Dark Souls: Black Dragon Kalameet, who is also a one-eyed black dragon.

Additionally, in the original King's Field, not released outside Japan, Guyra appears as a black dragon that "has lived in the forest and defended the people" since ancient times. This is similar to how Kalameet is fought in a forest in the past.
Contributed by Tubifex
When originally announced, the game was titled "Dark Ring". The name was changed to Dark Souls because "Dark Ring" can be seen as a euphemism for an anus.

This was the second time the name changed. The first time was also unintentionally risque; "Dark Race".
Contributed by DidYouKnowGaming