A Mysterious Black Knight Participating in the Fourth Holy Grail War
Berserker is Saber's fellow Knight of the Round Table known as Lancelot of the Lake. While still alive, Lancelot was the most loyal knight among Arturia's ranks. However, Lancelot winded up having an affair with Arturia's queen, Guinevere, and this fact was exposed by political enemies of the king. With Guinevere forced into execution for Arturia to save face, a distraught Lancelot killed several of his fellow knights in his attempt to save Guinevere's life. While Arturia forgave Lancelot's actions and Lancelot still pledged loyalty to her, his actions led to war and carnage throughout Britain and Lancelot was excommunicated from his duties among the Knights of the Round Table. Distraught that Arturia never admonished him for his actions, Lancelot was driven into madness and allowed himself to be summoned as a Berserker class in the Grail War so he could be slain by Arturia as atonement for his sins.
Berserker was created by Gen Urobuchi for his Fate/Zero novel series. His armor was designed by Hirokazu Koyama, who tried to give Berserker's character the appearance of a dark hero whose awesome power and speed would be a shocking contrast to the thin and weak looking appearance of the man behind the armor. The slit-like hole in Berserker's armor was the only thing remaining from the original design phase of his character's design. Character designer Takashi Takeuchi created Lancelot's appearance without his armor while in his normal and berserk states, with Takeuchi musing that "This guy is so unlucky" when he drew him in his berserk state. The second battle between him and Gilgamesh where they battled in the skies of Fuyuki with Berserker controlling a fighter jet was planned since early developments of the novel.
Berserker was added into the anime adaptation of Fate/Zero by Ufotable, being voiced by Okiayu Ryotaro for the Japanese version and Kyle Hebert for the English dub. Much of his character design and movements were rendered in 3DCG animation, particularly the black fog given off by his body coming from the effects of For Someone's Glory.
Berserker stands at 191 centimeters (roughly 75 inches) and weighs 81 kilograms (178 pounds). He is fully clad in a pitch-black suit of armor with a rustic helmet containing a slit that exposes the red glow of his fiercesome eyes. He has neck-length long purple hair and grey eyes. While still alive, his appearance was handsome as such where he was admired by many women. However due to the effects of Mad Enhancement, his face looks pale and ragged in appearance.
While under the effects of Mad Enhancement, Berserker's rationality and ability to think is limited as thoughts of bloodlust and murderous intent radiate through his mind. The mere sight of Saber will drive him into a blind rage as he will shift his concentration towards attacking her and ignoring the orders of his Master.
While still alive, Lancelot was one of Arturia's most loyal knights as such where he was one of the few people who knew of her true identity as a woman and they viewed one another as close friends. While still thinking greatly of her after the sins he committed, the fact that Arturia could still remain righteous in the eyes of others despite her flaws drove him into a epiphany where he rationalized that he would have to bring about her downfall.
Berserker was summoned to serve as the Servant of Kariya Matou during the 4th Holy Grail War. Throughout much of the Grail War, Kariya attempted to use Berserker to kill off Tokiomi Tohsaka's Servant, Gilgamesh, out of revenge towards him. Instead, the sight of Saber would lead Berserker to reject his Master's orders to attack her in a blind rage.
In the final day of the Grail War, Saber and Berserker would have a final confrontation with one another where Saber becomes shocked to discover that Berserker is Lancelot upon revealing his sword Arondight to her and his helmet breaks apart to reveal his face. This leads Saber to be hesitant to strike down her fellow Knight of the Round as she thinks Lancelot bares hatred for her rule under Britain and is prepared to be slain by his hands. However when Kariya can no longer supply Lancelot's high mana costs, the knight's movements halt and a desperate Saber stabs him through the chest. As Lancelot was dying, he regains his sanity to reveal to Saber that he wanted to be slain by her to atone for the sins he committed while still alive before fading away.
As a Berserker, Lancelot's stats are greatly augmented as a result of the Mad Enhancement ability given to the class, which comes at the cost of the knight's sanity. Unlike Hercules summoned as a Berserker in the 5th Holy Grail War though, Lancelot still retains his natural skills as a swordsman through the Eternal Arms Mastership skill which keep his skills from being dulled due to any kind of mental hindrances.
Lancelot possesses three Noble Phantasms for his use in the 4th Holy Grail War: For Someone's Glory, Knight of Honor and Arondight.
For Someone's Glory surrounds Lancelot in a dense black fog that serves to obscure his identity, status and abilities from other Servants and Masters. Its true ability is that it allows its owner to take on the form of other Heroic Spirits. But Lancelot is incapable of using For Someone's Glory to its full extent due to his mind being under the effects of Mad Enhancement. As a result, Kariya would have to make use of a Command Spell for Berserker to turn into another Servant with the Noble Phantasm.
Knight of Honor allows Lancelot to turn nearby objects he identifies as weapons into Noble Phantasms when they become consumed by the Black Knight's prana. Any objects he grabs using the ability become D-Rank weapons capable of harming a Heroic Spirit which can include anything from an uprooted electric light pole to even an F-15 fighter jet. Knight of Honor also works on the Noble Phantasms of other Servants as they still retain their ranks and abilities when they come under Lancelot's control. As a result, Knight of Honor becomes an effective counter against Gilgamesh's Gate of Babylon as Lancelot is capable of grabbing any fired weapons and making use of them to easily fend off a volley of weapon attacks coming from the King of Heroes.
Arondight is a sister sword to Saber's sword, Excalibur, which reveals Lancelot's true identity to his foe. When drawn, Knight of Honor and For Someone's Glory become sealed. However, Lancelot gains a large boost in his stats when Arondight is active and is highly effective against any magical being with a "dragon" attribute. Because Saber has dragon's blood running within her body, Arondight puts her at a great disadvantage when Lancelot draws the sword.