Why: Do we really need to remind you what happened at the Red Wedding?
Status: Dead. Before Arya slit his throat, she fed him a pie she made filled with the meat of his sons Lothar and Black Walder.
Why: For killing Syrio Forel, Arya's dancing instructor. He was the first person on her list.
Status: Dead. So dead. At a brothel in Braavos, Arya stabbed him in the eyes then slowly stabbed him to death while reminding him who she was.
Why: He was the mastermind behind the Red Wedding. Walder Frey couldn't have come up with that on his own.
Status: Dead. His own son Tyrion shot him with a crossbow while he was on the toilet. Arya probably doesn't love that she didn't get a chance to off him herself, but killing someone on the toilet has got to be some inspiration for her future assassinations.
Why: For torturing people at Harrenhal, and threatening to rape her.
Status: Dead. Arya killed him after he attacked her and The Hound.
Why: For gleefully ordering the execution of Ned Stark, and the execution of her friend Mycah. Also for being a really, really, really horrible person.
Status: Dead. Poisoned by Littlefinger and Olenna Tyrell. The only bad thing about Joffrey's death was that Arya didn't get to do it.
Why: For stealing her sword, Needle, and for killing her friend Lommy.
Status: Dead. With the help of the Hound, Arya stabbed him in the throat with Needle right after she got it back from him at an inn in Westeros.
Gregor "The Mountain" Clegane
Why: For the torture at Harrenhal, and for raiding in the Riverlands. And in general he's just a really awful person.
Status: Zombie. Oberyn Martell killed him, but disgraced and creepy Maester Qyburn brought him back to life as Ser Robert Strong with his experiments.
Sandor "The Hound" Clegane
Why: For killing Arya's friend Mycah, the butcher’s boy, on Joffrey’s orders on the Kingsroad back in season one.
Status: Alive. Arya left him for dead at the end of season four, but he was saved by Brother Ray (Ian McShane). Despite the fact that she left him for dead, they kind of liked each other in the end, so if their paths cross again she probably won't kill him. She let him suffer enough.
Thoros of Myr
Why: For selling Gendry to Melisandre and releasing The Hound, along with fellow Brother Without a Banner Beric Dondarrion.
Status: Alive and with The Hound, except now he has a man bun. In order to kill Beric Dondarrion for good, Arya will have to kill Thoros before he can bring his friend back from the dead (again). She's probably over The Hound thing considering how their storyline ended in season four, but only time will tell.
Why: For selling Gendry to Melisandre and releasing The Hound.
Status: Alive, and with The Hound, heading north to take on the White Walkers. Arya could kill him, but he'll probably come right back thanks to his friend Thoros of Myr, and the Lord of Light.
Why: For executing Ned Stark on Joffrey's orders.
Status: Alive. We haven't seen him in a long time. But he's not as important others on the list who are still walking around Westeros with beating hearts.
Why: For taking Gendry away from the Brotherhood Without Banners.
Status: Alive and headed to Volantis. She'll probably be back, and shell probably come to face to face with Arya. Melisandre tells Varys she will die in Westeros, so we're guessing she already knows her fate. And her death could be in Arya's hands.
Why: She falsely accused Arya's father, Ned Stark, of treason and had him arrested, which led to his execution on King Joffrey's orders.
Status: Alive, and sitting on the Iron Throne. And drinking lots of wine while standing on a giant map of Westeros. She has Zombie Gregor Clegane to protect her, but from what we saw in "The Spoils of War," she's not safe for long.