Gwyn, Lord of Cinder

Gwyn, Lord of Cinder is the final boss in Dark Souls and one of the original lords who vanquished the Dragons.

Location
Lord Gwyn can be found only in the Kiln of the First Flame.

Summoning
It is possible to summon Solaire of Astora to help in the fight if he survived in Lost Izalith. His summon sign can be found at the top of the staircase from Gwyn. Since the Kiln of the First Flame is a PvP hotspot, it can also be quite easy to find player summon signs if online.

Description
He wears an impressive set of royal drapings, with gold bands on his arms, and a crown atop his head. On his feet are what appear to be a form of moccasins and anklets, and he wields a greatsword imbued with the power of light and of the First Flame, which he uses to adequate effect. His face is that of an aged man with calm eyes, and he has impressively long, grey beard and hair of the same nature. When the Chosen Undead fights Gwyn in the Kiln of the First Flame; Gwyn appears to be  Hollow, evident by his haggard appearance, charred skin and missing eyes.

History
Before the flame existed, little of Gwyn's life is known, save that he had an uncle named Lloyd. He was surrounded by knights when he found the flame, and was dressed in his regalia, so it is clear that he has been a king long before that moment.

At the dawn of the Age of Fire, Gwyn discovered a Lord Soul along with the Furtive Pygmy, Gravelord Nito, and the Witch of Izalith. His soul embodied the concepts of light and energy, allowing him to manipulate them both, and generate a substance called lightning. They allied with Seath the Scaleless and amassed an army, and with their power, challenged the Everlasting Dragons for dominion of the World. His mighty bolts peeled apart their ancient scales, allowing them to be killed by other attacks, and they were ultimately vanquished.

And thus the Age of Fire began, and Gwyn became Lord of Sunlight, and the king of Lordran. He lived with his clan, who became a new and varied race known as Gods, in their city of Anor Londo. They often hunted the descendants of the dragons for sport, for which many of their powers were developed. This did not include Seath, for he received recognition for his deeds, and was made a part of the nobility.

When the flames began to fade, Gwyn and the other Lords did all they could to find a solution. The Witch of Izalith attempted to recreate the First Flame from her own Lord's Soul, but the attempt went horribly awry, mutating the Witch into the terrible Bed of Chaos, which spewed forth malformed demons. Seeing no other choice, Gwyn left Anor Londo and traveled to the Kiln of the First Flame, to link the First Flame, thus prolonging the Age of Fire. When he left, he divided the Light Soul among his clan and his children,  and granted parts to both the Four Kings and Seath.

In linking the flame, Gwyn sacrificed himself and his powerful soul provided fuel for the flames, prolonging the Age of Fire. Half of Gwyn's faithful Silver Knights followed him when he departed to link the Flame, "but they were burned to ashes in newly kindled fire", becoming the Black Knights that now wander Lordran. His Light Soul was able to keep the fire burning for decades, but it left Gwyn to hollow.

It is implied that at least one thousand years have passed when the events of Dark Souls begin. Gwynevere, Princess of Sunlight, Kingseeker Frampt and Darkstalker Kaathe give the Chosen Undead alternating viewpoints of Gwyn. Gwynevere claims that it is the Chosen Undead's duty to succeed Gwyn, stating that their success would "avert further Undead sacrifices"  and that without Fire, "all shall be a frigid and frightful Dark"  – a perspective that Frampt shares. As Gwynevere is actually an illusion,  whether or not they are being entirely truthful is left unresolved.

On the other hand, Kaathe asserts that the Age of Dark – the apparent "age of men" – would naturally follow the Age of Fire, but Gwyn, in dire fear of both the Dark and humans, resisted the course of nature by sacrificing himself to link the Fire. Unlike Frampt, Kaathe believes it is the Chosen Undead's fate to "destroy the fading Lord Gwyn, [...] become the Fourth Lord, [and] usher in an Age of Dark".

Army
Much of Gwyn's army of Silver Knights accompanied him to Link the Fire. When the flame was kindled it transformed those present into Black Knights, the disembodied spirits that roam Lordran. The remaining Silver Knights guard Anor Londo.

He formed the Four Knights of Gwyn: Dragonslayer Ornstein, the believed captain of the guard;  Hawkeye Gough, commander of the Dragonslayers;  Lord's Blade Ciaran, the assassin;  and the legendary Knight, Artorias the Abysswalker.

Gwyn's friend, Havel the Rock, was a general over his own warriors, which were presumably part of Gwyn's army. Friend-wise, Kaathe states that Frampt "lost his sense" and befriended Gwyn.

Family
Gwyn is the nephew of Allfather Lloyd  and father of Dark Sun Gwyndolin, whom he raised as a daughter due to Gwyndolin's affinity to the moon,  and Gwynevere, Princess of Sunlight. He also had another, unknown son, who was a god of war and inherited the sunlight through his status as firstborn. However, he sided with the Dragons, was promptly stripped of his deific status, and all references to him erased from Anor Londo and Lordran. He also had a daughter who was banished to sleep eternally on the Ringed City, protected by the Pygmy's descendants.

Dark Souls II
Although not explicitly stated, it is implied that the events of Dark Souls II take place centuries or millennia later  – more than enough time for several kingdoms to rise and fall in the time between. It is also shown that regardless of the Chosen Undead's decision to link the Fire or not following Gwyn's death, the cycle of Undeath still exists. At this point, Gwyn has long been forgotten – only recalled as the God of Sun  – and his only legacies are four of his surviving miracles: Lightning Spear, Great Lightning Spear, Sunlight Spear, and Blinding Bolt. The Sunlight Spear is stated to be "one of the ancient original miracles, said to have existed from the infancy of the very world",  but its relation to Gwyn is not mentioned, further reinforcing him being past recollection. Furthermore, the Blinding Bolt miracle was said to be created and then later forbidden by him.

The Old King Soul is dropped by the Old Iron King if he is defeated at bonfire intensity 2+. The soul is described as a "once magnificent soul" that can be used to make either the Blinding Bolt miracle or a Dragonslayer Greatbow, thereby creating some connection between the Old Iron King and Gwyn. The Old King Soul shares some traits, such as the appearance and description, with the Old Paledrake Soul, which implies that the Old Iron King may have just possessed a Lord Soul shard rather than Gwyn's own soul. The shard would, in this case, likely be the one Gwyn gave to the Four Kings of New Londo who, like the Old Iron King, pursued power for their own gains.

Dark Souls III
Gwyn is reincarnated, along with all other Lords of Cinder who followed him, in the Soul of Cinder. This last defense against the Ashen One is an amalgamation of all Lords of Cinder who ever linked the first flame. Using Gwyn's fighting style after its primary attacks proved fruitless, the Soul of Cinder serves as the final boss of Dark Souls III.

Strategies
Health and Stamina management are a must in this fight, as Gwyn will rarely give the player any chances to heal. It is heavily advisable to use a fast weapon to attack with, preferably one that drains little stamina. Heavy weapons are not recommended for this fight. It may be hard for the player to find a proper opening to fight back or heal as a result of Gwyn actively seeking the player. His attacks deal a great amount of damage if they connect. If blocked, his attacks will still deal considerable damage to the player as a result of the flame damage his sword deals. A good way to reduce the damage to a slight margin is by using shields with high fire defense, such as the Black Iron Greatshield or the Black Knight Shield, which can be dropped by the nearby Black Knights; however, care should still be taken as blocking a full attack chain will cost a lot of stamina and may eventually result in losing health or dying. The Gold-Hemmed Black Set can further negate the fire damage at the cost of less physical defense against his attacks.

The pillars in the arena can be used to block his attacks, however, Gwyn will easily move around them and continue attacking. It is possible for him to keep attacking a pillar that is blocking his path, giving the player a chance to heal, however, he may simply go around it.

Parrying is a high-risk, but incredibly efficient strategy. All of Gwyn's attacks, minus the kick and grab, can be parried. Using the Hornet Ring, a single riposte can erase a large fraction of Gwyn's health. However, any mistakes can end up badly for the player. Therefore, it may be preferable to opt for heavier armor for this strategy, as dodging is not the main tactic, and the additional poise and defense leaves some margin for error. It is ideal to block the first hit of his combo, and parry the telegraphed second hit. After performing a riposte, the player will have just enough time to Estus heal.

Summoning Solaire or other players can help ease the battle, giving a chance to heal or apply buffs. For Solaire, he may be able to land several hits before dying. By using the Black Knight Halberd or a spear type weapon you can hit Gwyn through the pillars and take little damage from his attacks.

MELEE STRATEGY While Gwyn does not provide for a lot of openings, especially if wielding a slow weapon like the Zweihander, it is possible, through using a shield with enough stability and having enough fire resistance, to use a circling strategy.

Keeping very close to Gwyn and keeping a shield up, the player can be dealt very little damage by the flaming sword by constantly strafing to the player's left. When Gwyn attempts to grab the player or kick them, the slower animation should enable the player to get behind Gwyn's back, thus making the attack miss. At that point, there's a small window to get an attack in. With a weapon with a strong enough attack to break Gwyn's poise, the player then has a full second to finish the attack animation and get the shield back up, effectively never breaking their guard.

Use of this strategy requires the player to keep a close look on their stamina bar.

Regularly, though, the player will have to heal themselves, unless the fire damage is completely negated. Using the pillar strategy outlined above is quite efficient. It is a good idea to keep one's health high enough to that a grab attack can't kill with one hit. Therefore, having 20 estus flasks is recommended.

Dashing Thrust
Used by Gwyn while he's dashing. Although it is one of his linear attacks, it is possible he may switch to a slashing combo midway. It is also one of his best attacks in terms of tracking the player.

Quad-Slash Combo
Gwyn performs this attack in quick succession and solid tracking. It begins with an angled slash, then a horizontal one, another angled and finally a horizontal slash once more. The angled attacks can be sidestepped if the player moves early enough.

Kick
Triggered regularly when blocking close to Gwyn, it causes a large drain of stamina if it connects while blocking.

Slash and Thrust
Occasionally Gwyn will interrupt his normal slash combo with a quick thrust afterwards. If it hits, the player will be stunned, leaving them open for further combos.

Slashing Upper Combo
Starts with a powerful horizontal slash, which takes a large portion of stamina, followed by two more hits. The first two slashes can be difficult to evade.

Charging Slash
A powerful slash used by Gwyn to break the player's guard.

Instant Dash/Double Slash
A very fast attack, which comes out of Gwyn's instant dash when he glides towards the player before slashing twice.

Explosive Hand
An unblockable grab attack that deals massive fire damage. It has a high horizontal hitbox, so it is possible to roll under it to avoid it. It's relatively slow and does not track well so player can simply walk backwards to avoid it. After knocking the player away, Gwyn will follow up with a jumping slash or dashing slash. It also leaves Gwyn open to attacks for a short time.

Drops
Gwyn's armor, the Great Lord Set, can be purchased from Domhnall of Zena during the next playthrough.

Trivia

 * Gwyn's design and lore seems to have been heavily inspired by Zeus of ancient Greek mythology.