Arya Stark

"Ser Gregor, Dunsen, Raff the Sweetling, Ser Ilyn, Ser Meryn, Queen Cersei. Valar morghulis."

- Arya Stark going over her death list

Arya Stark is the daughter of Eddard "Ned" Stark and Catelyn Stark, the youngest female child of the Starks and the older sister of Bran and Rickon Stark as well as the cousin of Night's Watchmen Jon Snow. She was a resident of Winterfell, later of King's Landing unitl her family was almost entirely eradicated from Westeros during the War of the Five Kings. She's now with the Faceless men of Braavos to learn how to become an expert assassin and take revenge for her fallen family members and friends. However the Faceless Men revealed her she cannot kill whoever she likes, and she must forget her past and identity by becoming "no one".

She is portrayed by Maisie Williams.

Personality
Arya is a fiercely independent child who is unconstrained by social expectations like gender roles, courtly virtues, class distinctions, and the expectations of her parents and siblings. A tomboy since she was young, she never aspired to be a "proper lady" as her older sister Sansa did. Before the series of events that shatter her innocence and destroy her support system, Arya is full of life, and she makes others smile just by virtue of her spirited indifference to rules.

Once she begins the journey to King's Landing, however, she endures a constant stream of loss and trauma. As she watches her pet, sword instructor, friends, and family members taken from her one by one, she becomes increasingly detached towards murder and death. This is only exacerbated when she is captured by the Hound and is exposed to his fatalistic worldview as they traverse the war-ravaged Riverlands, though the two develop a mutual reliance and almost grudging respect for each other. When she witnesses and learns of the betrayal and murder of her family at the Red Wedding, she becomes even more cold and driven to seek revenge on those who have wronged her and her family.

While she is initially horrified when she accidentally stabs the stable boy in King's Landing during the betrayal of her father and his men, by the time she and the Hound have fled the massacre at the Twins, she is able to kill without remorse and has accepted Syrio's belief that the only true god is Death. Following Yoren's advice to her before he died, she has taken to listing off the names of each person she intends to kill each night before she sleeps.

In the books
During her journey, Arya is subjected to many hard situations in the war-torn Riverlands. Her fiery personality prompts her to take the initiative and fight back, and so she is led to kill and ultimately wishes to murder specific characters herself. This course of action is supposed to end as of A Feast for Crows with her being an assassin trainee in Braavos, as the leader stresses becoming indifferent to death and killing. She continues, however, to repeat to herself the names of the people she wishes dead. Some names are added as she goes, and others are dropped when the character dies or becomes closer to her. She calls it a prayer, and ends it with the words Valar Morghulis. The names are:

In the series
The people on Arya's death list currently are:
 * Cersei, for her role in the execution of her father.
 * The Mountain, for leading the brutal torture at Harrenhal. Revived by Qyburn from his presumed death.

The people no longer on her list, because she knows they are deceased or believes them to be dead, are:
 * {Polliver}, for killing her friend Lommy, stealing her sword Needle, and taking part in the brutal torture at Harrenhal. Killed by Arya while repeating the same words Polliver said to Lommy when he killed him.
 * {Joffrey}, for ordering the execution of her father. Killed during his own wedding.
 * {Rorge}, for threatening to rape her. Killed by Arya just after adding him to the list.
 * The Hound, for killing her friend Mycah and being a Lannister lackey. Severely injured by Brienne of Tarth and left to die by Arya, though unbeknownst to her, he is still alive.
 * {Tywin Lannister}, for leading the Lannisters against her brother. Killed by ​his own son Tyrion Lannister.
 * {Ser Meryn}, for killing her dancing master Syrio Forel and aiding Cersei in her coup. Killed by Arya in a Braavosi brothel, disguised as an underaged prostitute.
 * {Walder Frey}, for his role in killing her brother and mother. Killed by Arya at the Twins.

Others
Arya stated she would have added the Freys to the list after the Red Wedding but she did not know the names of those responsible for her brother's death.

She also killed a number of people who were not on her list herself:
 * a Red Keep stableboy, during the purge of the Stark household
 * several soldiers of Amory Lorch, during the attack on Yoren's recruit caravan
 * a Bolton guard at Harrenhal, to escape the castle
 * a Sarsfield squire, during the fight at the Crossroads Inn
 * Dareon, at Braavos after noticing he was a deserter
 * a Braavosi insurance salesman, under orders of the kindly man
 * The Waif, in the TV series only, for attempting to kill her
 * Lothar Frey, in the TV series only, for being one of the orchestrators of the Red Wedding and killing Robb's stillborn child
 * Black Walder Rivers, in the TV series only, for killing her mother

She also initiated and, along with Jaqen H'ghar, Rorge, and Biter, took part in the killing of eight Harrenhal jailors, an event that would be remembered as the "weasel soup," from the nickname she used at the time.

In the TV series, for a while, Arya added the Red Woman, Beric Dondarrion, and Thoros of Myr to her list, because she was upset the Brotherhood Without Banners let Melisandre take Gendry away. She later phased them out of her list, presumably because they didn't do anything remotely near what other people in the list had done.

Ilyn Payne, the executioner who beheaded her father, was also phased out of her list, maybe because he was just a hired hand. Furthermore, the actor who plays Ilyn Payne developed pancreatic cancer after Season 1 and very nearly died, so his return to the TV series became uncertain.

Arya later revealed to the Waif that she was no longer intent on killing the Hound when she left him.

Arya's list logically only contains those whom she knows have committed crimes against her or her family. Despite committing great crimes against her family, Littlefinger, Roose Bolton and Ramsay Bolton are not included in Arya's death list, as she never learnt of Petyr Baelish's direct involvement in betraying her father; or Roose Bolton's in the Red Wedding, much less that he personally killed Robb. She is also unaware of the fact that Ramsay sacked Winterfell.

Powers

 * Disguise: Arya can hide her true physical appearance under a disguise, due to her training with the Faceless Men. She has learned to control this power quite well, as shown in her early realesed chapter of the sixth novel. In the TV series, this skill shows no magical trait, however, being depicted as simply wearing a dead person's face. Regardless of the version, Arya learns to handle this tehnique, which will later work out in her favor, such as when she assassinates Meryn Trant in the Season 5 finale and later Walder Frey in the Season 6 finale in Game of Thrones, or Raff the Sweetling in the sixth book, The Winds of Winter.
 * Skinchanging: The ability to inhabit the body of an animal and control its actions by opening the "third eye". Arya has shown to have this power, as she can slipp into her direwolf, Nymeria, while asleep and wargs into cats in Braavos. It's not shown in the TV series.

Abilities

 * Swordsmanship: Unlike little girls of her social status, Arya learned to fight with a sword and has above-average swordplay skills, being trained by Syrio Forrel in the art of the Braavosi Water Dance. Arya showed her skills mainly during Amory Lorch's attack on Yoren's recruit caravan, when she kills several Lannister soldiers.
 * Archery skills: Arya is showed to be fairly skilled with a bow. In the TV series, she is able to out-shoot Bran, loosing an arrow at the target while farther than him.
 * Assassin skills: Her Faceless Men training has provided Arya with strong assassin qualities, such as being able to detect lies of the others or depict ingredients, potions, herbs and poisons.
 * Eye-Less Combat: Thanks to her temporary blindness and combat training, Arya has arguably developed stronger senses than normal humans, to the point that she can move and fight in the dark. This ability is shown mainly in the TV series and, in the eighth episode of the sixth season, Arya takes advantage of this new skill and kills the Waif in the darkness of her hideout.
 * Multilingual: Arya is fluent in the Common Tongue (English) and Braavosi. She has also shown basic knownledge of High Valyrian.

Trivia

 * So far, Arya is the only POV character who has POV chapters in the whole series.