Diane「ディアンヌ」 is the Serpent's Sin of Envy of the Seven Deadly Sins. She is a member of the Giant Clan and is thus much larger than ordinary people, including her fellow Deadly Sins. Her Sacred Treasure is the War Hammer Gideon, which she uses in conjunction with her inherent power, Creation.
During the New Holy War arc, Diane's strength was fully acknowledged by the former King of the Giant Clan, Drole as he himself died protecting her after declaring her as his successor, making her the next potential ruler of the Giants as well as the unofficial "Giant Queen." She is also currently the fiancée to King, who is the current King of the Fairy Clan.
Appearancehuman being. She is a fair maiden, described as "lovely, beautiful" with purple eyes and medium length brown hair which is tied up into large twin tails. She has a well-endowed and curvaceous body. Similar to most of the other Seven Deadly Sins, her facial appearance is relatively childlike and has shown little change over the years. Diane's wanted poster depicts her with light-colored hair. Her symbol, which is of the Serpent, is located on her left outer thigh.
When she was still a child, Diane wore ragged clothing until King made her a new set. Her clothes during the earlier part of the series resemble what King made for her, having sewn it herself by using leather derived from Dusk Bison skin. Her earlier attire consisted of a short-sleeved one-piece orange suit, boots with five crossed laces that extend almost up to her knees, and two finger-less gauntlets of a blue-grey leathery material covered in shiny steel stud - with the right gauntlet having been destroyed by Gilthunder during the fight in the Forest of White Dreams. She also wore a backpack previously used by Meliodas. She wears a short purple sleeveless dress with white puffballs down the front while human size or the Boar Hat uniform while serving at the bar.
Ten years ago, Diane —as a Holy Knight— wore a full-body orange armor with a unique helmet like the rest of her fellow Deadly Sins.
After Hendrickson's defeat, Diane wears clothes made by King  that are almost the same style as her previous one, except for an inverted triangle cut on the chest and the skirt. She also wears black underwear resembling bike shorts underneath the skirt.
During the New Holy War, Diane wears new clothes made by Merlin.
Diane is a very friendly Giantess and is also very confident regarding her abilities, appearing to generally consider Holy Knights as weak. She cares very much about her captain and holds very strong feelings for Meliodas, often cuddling him  and becoming very delighted from compliments. Her feelings are strong enough for her to overcome her fears for his sake. Diane can become extremely fierce and hostile towards anyone who threatens her friends. Diane also gets jealous when Meliodas does perverted things to other girls.
Due to her size, she cannot help Meliodas in any way other than fight for him. She has expressed her strong desire to be smaller, contrary to Elizabeth's desire to be strong. Despite Diane stating that she has no interest in humans, she still selflessly saves people who are in danger like when she risked her life to protect the elderly man in Vaizel and Zeal.
Despite her brave and strong appearance, Diane is a somewhat emotionally fragile person as shown by her hatred of loneliness. This was portrayed when she was a child and insisted that King stays by her side when she was sick instead of getting herbs to heal her and when she waited in tears for him to return to her. Diane showed the same kind of feelings towards Elizabeth after she was kidnapped by Vivian.
700 years ago
Many years ago, Diane left the Giant's Clan due to her hatred for fighting. After her departure, she formed two rock-like golems to accompany her, despite either of them being unable to talk. She was always alone playing with them as there were no other living beings who would accept her.
At one time, however; Diane found an injured King lying unconscious on a riverbank and nursed the fairy back to health. King, who had taken a hard blow to his head, had lost all memories of his past and in his gratitude spent the next five hundred years playing with and protecting Diane. Diane later met an old man, a human, who offered Diane and King some food despite them being Fairy and a Giant. King was wary with the old man and told Diane to be careful around humans. Due to unknown reasons, Diane ended up getting a fever, in which King panicked due to Fairies never having fevers and went out to get herbs. However, Diane stopped him, telling him to not ever leave her side since she didn't want to be alone anymore. The old man who gave them food found them, and concocted a herbal medicine for Diane's fever, eventually curing her of her ailment. As soon as Diane got better, King and Diane ended up playing tag with each other, as King told her that if she caught him, he will grant her a wish.
Diane took it seriously and caught King, but ended up getting her clothes ripped off in the fray, leaving her entirely naked, much to King's dismay. King ends up making her new clothes and the two went to visit the old man hunter's place, only to find more houses had sprung up around there, and that the man they believed was the hunter they had met was actually the late hunter's grandson. After leaving the forest, King told Diane about marriage between two humans who love each other. Diane asked if King loves her, which he flushed to, but agreed. Diane thus chose to use King's promise to make him always love her. He agreed wholeheartedly. Later that night, King ended up remembering who he is through various flashbacks in his dreams and found out that the village close by was on fire. King told Diane to stay back as he went to the town, promising to come back. Diane waited in tears, hoping for King to return, only to find King return and strike her with a flower to her spine to erase her memories of him. Diane eventually awoke from her slumber without any memories, but curiously picked up King's flower and walked outside. She rejoins the Giant's Clan afterward.
16 years ago
Several hundred years later, Diane had grown into a woman and was in midst of being trained by Matrona to become the strongest Giant warrior alongside another fellow giantess, Dolores. One evening, Diane overheard Matrona's plans to make Diane the strongest Giant warrior ever. Disliking Matrona's plans for her, Diane made up her mind to leave the village once more. She goes to find Dolores and run away with her, but Dolores declines. Dolores explains after much thought, the Giant's village is the only place where they will ever be accepted, and that there was nothing to fear once you've been accepted.
Diane left the village once more alone and soon entered into a petty argument with a group of knights called the Knights of the Golden Wheats, who had discriminated against her for being a giant. Meliodas stopped them, then questioned Diane if she was frightened; his having treated her as he would, a normal girl of his size made her feel as though she was his size, i.e., small. Diane's encounter with Meliodas has her run straight home to tell Dolores that there was another place they could be accepted. When Diane arrived at the village, Dolores was revealed to have been killed by mountain bandits on a bodyguard job. After Diane learned that Matrona was the one who sent Dolores, she punched her in anger, upset knowing her friend would rather die, than wanting to fight.
The day after, Diane and Matrona were hired by the Knights of Liones as mercenaries to help in taking down foreign savages. This was all a ruse however, as the knights' true objective was Matrona, looking to gain reputation and prestige for taking her down. Diane and Matrona engaged in a battle against the traitorous Holy Knights. In the midst of the brawl, a poisonous arrow was about to hit Diane, but Matrona took the arrow in her place, severely crippling the Giant warrior chief. Despite being weakened by the arrow, Matrona used the last of her strength to take down Gannon and 330 other Holy Knights before supposedly dying. Diane mourned for Matrona's death before being captured by the Knights of Liones and arrested under false crimes. She was sentenced to capital punishment under the pretense of killing Matrona out of envy, along with the deaths of 330 other Holy Knights to an attempt to silence all witnesses. As her punishment was read aloud, Diane was saved at the last moment by Meliodas who gained legal custody over her. Sometime after this, Diane officially became a member of the Seven Deadly Sins and became acquainted and friendly with all the other members, including King, with whom she did not remember or recognize at all.
12 years ago
While on a mission to wipe out a group of vampires who had taken over Edinburgh castle, Diane, who was partnered with King, were suddenly weakened due to a drunken Ban's deliberate use of Snatch and as a result, the two had a hard time in the battle against two Vampires, Mod and Ganne until they were saved by Gowther who had made the two vampires believe he was a part of their family and started to kill and attack one another. Diane and King were soon upset over Gowther for not coming sooner, who revealed he wanted to make it exciting.
10 years ago
The Seven Deadly Sins, including Diane, were summoned to a castle to meet the Great Holy Knight Zaratras sometime after defeating the troll queen and, at the same time, destroyed the Great Druid Altar. On their way, Diane speculated that the Great Holy Knight might reward them in their last mission, though Merlin predicted that it will be a scolding from their superior. When they find him dead, they are ambushed by all the Holy Knights in the kingdom, with Diane later being able to escape and reach the Forest of White Dreams, where she forced the indigenous Hide-and-Seek to hide her, lest she goes on a rampage.
Abilities and Equipment
As a member of the Seven Deadly Sins, Diane is shown to be incredibly strong. She was able to punch the ground and use it to stop a horde of bugs from destroying a town. She has also shown to have great endurance as she was able to resist Gilthunder's lightning and even break free from it. As Matrona (normal human size), she possesses incredible physical strength and speed which she displayed during the fighting festival's preliminaries by defeating more than ten men quickly and with ease. Even as a young child, Diane demonstrates an extraordinary connection with nature, being able to create two Golems. Matrona, who trained her all her life, said that Diane had the potential to become the strongest warrior of the entire Giant Clan.
Being a giant, Diane is able to perform staggering feats of strength, able to clash with the likes of Meliodas in terms of strength and even break through barriers capable of withstanding meteors with a single punch. She can swing a hammer with a weight of 998 kg (2200 pounds). Due to her giant size, this speed is reduced to nil, but when shrunken to human size her speed increases and is able to dodge rapid arrows shot by a foe of similar ability such as Gowther. Diane has great endurance as she is able to withstand several mortal blows, such as being pierced through the shoulder and thigh and still move fast enough to save citizens from collapsing buildings, and still retain consciousness even after losing blood and taking a further beating.
After passing the trial, her connection to the earth increased to where she can increase her power farther while dancing. According to Melascula, her strength became comparable to Drole's. Drole himself believed that eventually, she will become a greater ruler of the Giant Clan than himself because her love made her stronger than mere combat power.
- Main article: Creation
創造Kurieishon」: This ability, which is exclusive to members of the Giant Clan who have a deep connection with nature, enables Diane to manipulate the earth.
- Drole's Dance: A technique created by the giant king, Drole. By performing a special dance, Diane is able to increase her connection to the earth, while increasing her power level the more she carries it out. Diane mastered this technique after going through Drole's trial.
- Trinity Attack: High Tension Rush「
三位一体合技 怒濤の乱撃Toriniti Atakku: Hai Tenshon Rasshu; literally meaning "Triple Combine Technique: Raging Scuffle"」: A triple combined attack in which King attacks the opponent with Chastiefol in his sixth form at the same time that Gowther creates many illusions of him to confuse the enemy and Diane uses her Drole's Dance to increase their power level. 
- Gideon: Diane's sacred treasure; Gideon, is a war hammer designed for the Giant Clan. It is made of a material that is stronger than steel and weighs approximately 2200 pounds. It is able to draw out the full capability of her ability, Creation.
In her human size, Gowther assessed her strength level to be at 950.
After passing the trial, her power levels are as follows:
Performing Drole's Dance, her power levels are as follow:
Seven Deadly Sins
Diane and Meliodas are both members of the Seven Deadly Sins. She was in love with Meliodas for treating her like a normal size girl, so much that she immediately desired to fornicate with him after shrinking in size. She often gets very jealous of other girls who she suspects of having a close relationship with the captain and deals with it by raging at him.  Her future dream was to become little and have children with Meliodas. She respects him a lot and calls him captain. However, her feelings of love toward Meliodas disappeared as she regained her memories of King, thus falling in love with the fairy. She still shows respect and care for Meliodas afterward. After passing her trial and learning about Meliodas and Elizabeth's curse, Meliodas comforted Diane who felt bad for not knowing, and in turn, Diane became all the more protective and supportive of both him and Elizabeth as her friends. After regaining her memories Diane often joins Hawk in scolding Meliodas for groping Elizabeth.
Diane and Ban are both members of the Seven Deadly Sins. They are generally friendly with each other and are shown to have a teasing relationship. They tend to show a bit of rudeness to each other when they converse. They are shown to have strength rivalries by arm wrestling, which Diane is shown winning by using only a finger. Despite their rivalry, Diane is shown to care for Ban, getting upset when he didn't wear the new outfit she and King bought for him. Ban is aware of Diane's abilities and is shown to worry twice over her raging.
Diane and King are both members of the Seven Deadly Sins. When she encountered him after ten years, she was shown to be happy to see him and didn't appear to be aware of King's love for her. When Diane was a child, she spent five hundred years playing and forming a deep friendship with King after she had rescued his unconscious body from a river. While playing a game, King promises to grant Diane a wish if she could catch him. After winning, Diane asks King if he loves her. After saying yes, Diane asks him to love her forever to which he agrees. However, King begins to regain his memories and has to go back to his home. He breaks his promise of not leaving her after he doesn't come back, leading to her memories of her time with him being erased. After King saved her from Helbram, Diane began to regain her memories of their past and her love for Meliodas was replaced with King. When King went missing, Diane grew upset and began to cry as she wanted to tell him how she feels. She claimed that she would die of loneliness if he were gone. It is believed that Diane still loved King even when her memories were erased, but she could not recall King at the time and loved Meliodas in King's place. Eventually when Diane's memories returned, she and King kiss, and they become a couple. During the final battle against Demon King, King proposed to Diane to which she happily accepts.
Diane and Gowther are both members of the Seven Deadly Sins. They are fairly friendly with each other. There was an instance where Gowther revealed her true height to the other Sins, and she grew very upset at him, calling him a jerk. After finding out Gowther erased Guila and Zeal's memories of each other, Diane became furious and battled the Goat sin. Gowther erased Diane's memories using Lost World. When she regained her memories and returned to the other sins, Gowther began regaining his own. When he tried to use Lost World on himself out of fear for the new feelings, Diane stopped him and encouraged him to let them come. Diane comforted Gowther, and he thanked her for helping him choose the right path. The two now appear as good friends. During her travel to the past memories as Drole, she met Gowther of 3,000 years ago. As Gowther left Drole (Diane) to fight a demon, he tells her "Until we meet again." When Gowther regains his memories, Diane repeats this, recalling how they have met again.
Diane and Merlin are both members of the Seven Deadly Sins. Diane seems to like Merlin and has a good relationship with her as she was displeased when Merlin didn't rejoin the Deadly Sins. Diane holds Merlin very highly, seeing her as a genius due to creating a pill that will shrink her for seven hours. They are on good enough terms that Merlin is more than willing to use her magic to shrink Diane to human size whenever it is necessary, and she even made new clothes for Diane as well. Merlin was the only one who she depended on to find King after he went missing for days.
Diane and Escanor are both members of the Seven Deadly Sins. Despite being teammates, Diane was shown to be wary of Escanor when he was at his prime, and would rather not make an enemy of him. Diane also sees Escanor as a good and reliable guy.
At the beginning, Diane disliked Elizabeth as she was jealous of her close relationship with Meliodas. She also envied her small stature and her abilities to be able to take care of Meliodas when he was sick or injured. However, after seeing how courageous Elizabeth was when she sacrificed herself for innocent citizens, they developed a closer relationship and Diane acknowledges her, even stating that she doesn't mind fighting for her. Diane later grew to care for Elizabeth as a dear friend, as she was worried about her when she was kidnapped. Diane also supported Elizabeth's love for Meliodas after regaining her love for King. After learning of her and Meliodas' curses, Diane's loyalty and protectiveness of Elizabeth as her friend only grew.
Not much is known about Diane and Bartra, but Bartra seems to trust Diane like any other Deadly Sin.
Diane met Howzer during Vaizel Fighting Festival while disguised as Matrona in a human-sized stature. After knocking him out in their battle, Diane apologizes and shows remorse for having hurt him. Howzer then develops feelings for Diane, and they form a friendship. Howzer protects Diane after she is severely injured by Dreyfus and Helbram. Gowther assessed that the only reason Howzer had been with the Deadly Sins was because of Diane, and he appeared to be happy when Diane completely lost her memories of King, thinking that the rivalry for her attention with King wouldn't exist anymore.
Despite Dreyfus heavily injuring her and almost killing her, Diane still asks Dreyfus to help rescue Elizabeth and doesn't seem to hold a grudge against him.
Diane and Guila were enemies and battled each other while in the Necropolis. However, when Guila realized that a heavily injured Diane was being framed by Dreyfus, she regretted the way she had treated her. These feelings were strengthened when Diane protected her younger brother, Zeal, from a falling building. This caused Guila to instead fight for Diane, protecting her from the Grand Masters alongside Howzer.
Matrona was once Diane and Dolores' teacher who trained them into becoming strong Giant warriors. Despite Matrona being Diane's legal guardian, Diane disliked Matrona's warrior life and her lack of empathy. Diane and Dolores wanted to have a peaceful life and not fight in battles, but Matrona refused to accept this. Despite her dislike for Matrona, Diane greatly respected her for her bravery and loyalty to her Giant Clan and greatly mourned Matrona's supposed death. Diane respected her enough to use her name as her alias during the Vaizel Fighting Festival. After learning she was still alive, as well as fighting alongside her once again, and even meeting her new family, the two have since buried the hatchet, and have finally learned to accept one another.
Dolores was a close friend of Diane during her time at the Giant Clan. The two share a love for a peaceful life outside of the Giant Warriors, but Dolores was too meek and timid to do anything about and was sadly killed at the battle.
As the former king of the Giants and a member of the Demon Clan's Ten Commandments, Diane viewed Drole as a powerful enemy. During the Great fighting festival arc, Diane was visibly shocked by Drole's abilities and combat skills, as they both outmatched and canceled out her own. After being confronted by him and the former fairy king, Gloxinia in the forest, Diane was more than prepared to fight them alongside King, which impressed Drole. When they revealed their intention to betray their comrades, and then later when the two ancient kings send her and King to the past as part of their trial, Diane learned much about Drole, the holy war, and the events that lead to them joining the Ten Commandments. After passing the trial and regaining her memories, Diane began to view Drole as an ally and even seemed to have a newfound respect for him. Drole, in turn, showed even greater respect towards Diane for how she passed her trial, believing that eventually, she could be the next ruler of the Giant Clan. During his final fight with Chandler, he helped her escape, and told Diane how kind she is, and how that kindness would make her a better ruler of the Giant Clan than he ever was, stating that he would gladly become the shield for the future "Giant Queen".
- Meliodas, Diane & Ban vs. Guila: Indecisive
- Griamore vs. Matrona (Diane): Win
- Matrona (Diane) vs. Howzer: Win
- Meliodafu vs. Matrona (Diane): Draw, interrupted
- Diane vs. Helbram: Win
- Diane vs. Gowther: Indecisive
- Meliodas, Diane, Merlin, Slader & the Holy Knights of Camelot vs. Galand: Lose
- Diane, Gilthunder, Howzer & Gilfrost vs. Earth Crawler: Win
- Diane & King vs. Drole Golem & Gloxinia Servant: Win
- Seven Deadly Sins vs. Chandler: Indecisive
- Search-and-Destroy Force vs. Demons: Win
- Gowther, King, Diane & Elizabeth vs. Mael: Win
- Seven Deadly Sins & Four Archangels vs. Zeldris & Original Demon: Win
- Seven Deadly Sins, Four Archangels & Zeldris vs. Demon King: Win
- King & Diane vs. Galla: Win
- In Arthurian legend, Diane could possibly be a reference to Diana of the Wood due to her strong connection to nature.
- According to the databook(s):
- Diane's special skill is a defense
- She has no hobby
- Her daily routine is being energetic
- Weak Point: Bugs
- Birthplace: Megadozer
- What she likes about herself: Her eyes
- Dream/Hope: Become the giant clan’s best dancer
- Regrets: That she only ever fought with Matrona
- The most embarrassing thing in her life: Was there something?
- What she wants the most right now: Her lost memories
- Favorite animal: Cows, pigs, sheep
- Favorite smell: Green and flowers (King too)
- Her favorite food is pork
- Her charm points are her pigtails
- Her complex is her height
- The person she respects the most is Matrona
- A person she doesn't want to make an enemy of is Escanor.
- According to the King & Diane Pair Sin Guide Book:
- Diane isn't as assertive with King like she was with Meliodas because she would get embarrassed.
- She likes that King watches over her.
- She never thought of eating Hawk Mama as she did with Hawk.
- She loves King no matter what form he is in.
- She would like to get some girly clothes from King.
- King's new wings look scary to her.
- Diane is entomophobic, i.e., has a fear of insects.
- Diane told everyone that she is 29 feet tall, but Gowther pointed out that she is actually 30 feet in height.
- Due to her immense physical size, Diane is unable to sleep inside the Boar Hat, so she sleeps outside. Obviously, she can sleep in the bar when she is in a shrunken form.
- Diane tends to cover her face with her hair whenever she is embarrassed or shy.
- Nakaba Suzuki mentions that Diane's age in terms of human years would be slightly younger than Elizabeth.
- The Sin of Envy is usually symbolized with a Dog and the color green.
- In the Nanatsu no Taizai Popularity Poll, Diane was the 5th place for postcards (217 votes), but the 7th place (3781 votes) including online votes.
- She made a cameo appearance in episode 9 of Saenai Kanojo no Sodatekata.
- According to Meliodas, her measurements (in her shrunken form) are 91-58-90 (36-23-35).