Best: Never Let Me Go (2010)
Knightley stars alongside Andrew Garfield and Carey Mulligan in this heartbreaking adaptation of Kazuo Ishiguro's bestselling novel.
As Ruth, she's caught in a tussle with Kathy (Mulligan), for the affections of Tommy (man of the moment Garfield- can you blame them?).
The three have grown up at the mysterious Hailsham boarding school, where a grim sense of foreboding is a cornerstone of the curriculum.
Despite being punishingly sad, it's worth getting swept up in the thick atmosphere Mark Romanek creates and appreciating the heartfelt performances of the central trio.
Worst: Silk (2007)
Keira is left little to do but mope around looking photogenically winsome, in a film which does little else but mope around and look pretty.
Knightley's not the only one coasting here: Michael Pitt's talents are totally invisible too. He's a French silk merchant who falls for a concubine while on business in Japan.
All the while, Knightley's hard-done-by wife sits at home looking miserable. She might be the queen of period fare, but here she's defenceless against the crippling lack of substance.
Best: Pirates of the Caribbean: The Curse of the Black Pearl (2003)
As the blockbuster that put Knightley in front of the eyes of the world, made her a household name and hoisted her to the top of the list of Brit actresses in Hollywood, Pirates put fun first and foremost.
Of course she looked devastatingly pretty throughout, but her damsel in distress was given a few chances to show a bit of personality: she wasn't just a plot beat in need of rescuing.
It was one hell of a blockbuster to star in as your first biggie, and even the disappointing sequels haven't been able to sully the straightforward charms of the original and (by far) the best.
Worst: Pirates of the Caribbean: Dead Man's Chest (2006)
This sequel took the same ingredients that went into the first film and added a bit more money, but somehow the DNA of the original is barely noticeable in this shambolic mess.
Knightley's striking bone structure make her extremely unconvincing in her 'cabin boy' disguise, and the plot seems hell-bent on extinguishing any real chemistry, keeping Jack Sparrow action near the minimal legal requirement, and sending Orlando Bloom on an extremely boring mission to make amends with his dad.
The final insult comes when you realise you're going to have to sit through it all again if you even want an ending.
Best: Doctor Zhivago (2002)
Although not quite the equal of David Lean's majestic epic, this TV take on Boris Pasternak's classic novel was another early example of Keira's talent.
It's no small task to succeed Julie Christie in a role, but Knightley summons enough beguiling screen presence to be able to convince as the kind of lust object who would haunt you throughout your life.
She also proves capable of handling the opposing beats of fear and tenderness required when she's acting opposite Sam Neill (Komarovsky) and Hans Matheson (Zhivago) respectively.
Worst: Princess of Thieves (2001)
This TV movie casts Knightley as Gwyn, the swashbuckling daughter of Robin Hood and Maid Marion.
When Robin is imprisoned by the Sheriff of Nottingham (Malcolm McDowell), it's up to Gwyn to get Prince Philip on the throne before King John makes it his own.
This is nowhere near as much fun as Robin Hood: Prince of Thieves , and the TV budget isn't well-masked. The clunky script doesn't exactly play to Knightley's strengths either (she fails to convince as a resourceful, battle-ready farmhand).
Best: Pure (2002)
Stripped of big-budget trimmings and period finery, Keira turns in a solid performance here as a drug-addicted pregnant teen... but it's not quite depressing as all that sounds.
In fact, her character's is a ray of hope in the life of Paul (Harry Eden), a poor moppet who has been abandoned by his dad and left to look after his junkie mum.
Her relationship with Paul gives the movie a buoyancy that makes it easier to get through the tougher moments. Knightley works well with Eden, who gives a touchingly naturalistic performance.
Worst: The Hole (2001)
This Brit teen horror is another blot on Knightley's early CV. Her smug, plummy performance is enough to irritate her staunchest defenders, and she's probably not even the worst thing here.
There's barely any tension for one thing, and it's hard not to wish for all of these public school oiks to be despatched as quickly as possible.
If you couldn't be any less engaged, the narrative structure, which aims at smart, simply serves to make things even more boring.
Best: The Jacket (2005)
The movie itself is far from perfect, but this was another chance for Keira to show that she could actually act, and is a welcome argument-winner against anyone who claims she's only ever any good when stuffed in a corset.
Her brittle but damaged Jackie falls into a relationship with mysterious Gulf War veteran Jack (Adrien Brody), who just might be a time-traveller she met as a young girl. She also adopts a convincing American accent to go with the grunge chic look.
Worst: Love Actually (2003)
Knightley is unfortunate enough to star in possibly the worst segment of Richard Curtis' portmanteau romcom (surely only Kris Marshall's American adventure can compete for the crown?)
She's literally not asked to do anything beyond pout prettily and giggle as a woman whose hubbie's best friend is in love with her. If it wasn't for Bill Nighy we'd have never made it to the end.
Best: Pride & Prejudice (2005)
Matthew McFayden can't top Colin Firth's iconic Mr Darcy, but Keira does a fine job as Jane Austen heroine Elizabeth Bennett, in Joe Wright's lavish but accessible adaptation.
Yes, there's plenty of frockage, but Lizzie's far from pristine and idealised. Knightley delivers feistiness aplenty, holding on to the belief that she should marry for love rather than money.
Her performance secured her an Oscar nomination that year, and acted as a defiant 'In Your Face!' to her detractors.
Worst: King Arthur (2004)
Knightley wasn't the weakest link in this revisionist stab at the Camelot legend, bringing enough chutzpah (if not the physical presence) to just about pass muster as a Woad-warrioress Guinevere.
It's just the rest of the film is so damn boring, there's nothing to carry this beyond the 'meh'. Clive Owen was disappointingly bland as Arthur, and the film didn't generate enough excitement or tension to make up for the absence of any magic.
Best: Atonement (2007)
It's hard to argue with the fact that Knightley seems to produce much of her best work under the watchful eye of Pride & Prejudice director Joe Wright. The pair are rumoured to be teaming again for an adaptation of Anna Karenina which, should it come to pass, could be something very special.
By this point we knew that Knightley could deliver in the pristine gracefulness stakes, but she also manages to generate an affecting chemistry with James McAvoy with minimal screentime.
Credit's also due for making a plummy, privileged rich girl so deserving of our sympathies.
Worst: Star Wars: Episode I - The Phantom Menace (1999)
Knightley had an early brush with mega-budget blockbuster movie-making here, but you'd be hard-pressed to spot her.
Taking advantage of the striking likeness she had to Natalie Portman when the two actresses were young, she played Sabé, one of Queen Amidala's ladies-in-waiting.
She basically dresses up in the queen's finery so that Padmé can swan around pretending to be a handmaiden. When she is on screen she's heavily caked in make up, and the queen is often played by Portman anyway, to preserve the 'twist'.
Best: The Duchess (2008)
Knightley earned great notices for her role in The Duchess . She seems extremely comfortable carrying the movie, and refuses to allow her performance to be dominated by the impressive hair, make-up and costuming.
Playing Duchess Georgina Cavendish, she gets to flaunt her natural charisma as the fashion-forward blue blood, while also being required to flex her acting skills when she gets stuck in a loveless marriage with Ralph Fiennes archly-haughty Duke.
Worst: London Boulevard (2010)
William Monahan has an enviably strong screenwriting career, but he didn't seem so deft at directing when he adapted Ken Bruen's novel.
He assembled a top-notch cast, but failed to generate any heat, with London Boulevard under-delivering on almost every level. It doesn't seem to know if it's a thriller or comedy, without enough thrills or laughs to convince as either.
Knightley didn't exactly have to stretch herself as a young movie star, intent on avoiding the glare of paparazzis' flashes, but it somehow feels fumbled, with an unconvincing accent, and a complete lack of chemistry with Colin Farrell.
At least she's not alone, as it's a case of stilted performances all round. Unsurprisingly, this had a hushed roll-out into cinemas and swiftly disappeared afterwards.
Best: Bend It Like Beckham (2002)
Just before she was being touted as the next big thing, Knightley shows a rare, relaxed side of herself in this ladies' football comedy.
Despite being the team's star striker, Knightley holds back in a support role, but she still managed to shine and grab plenty of attention.
Gurinder Chadha's feelgood comedy held absolutely no surprises, but thankfully there were enough laughs, charm and even a decent stab at romance to cover over the predictability.
Worst: Pirates of the Caribbean: At World's End (2007)
It feels mean-spirited to keep sticking the boot into the Pirates sequels, but when the leading lady has been very vocal about the lack of a shooting script, it's hard to get into this movie's corner.
Fairly early on, any chance of this being a streamlined, neatly-tied-up conclusion to the overblown Part II were dashed. With Elizabeth Swann off on a meandering mission to save Jack Sparrow via a visit to Chinese pirate Sao Feng (an underused Chow Yun-Fat), it feels like it takes an eternity before anything that could be designated 'fun' arrives.
Script-deprived Knightley seems to have about as much idea about her character, the movie's tone, and what the bloody hell's going on, as we do.
Best: The Edge of Love (2008)
Keira Knightley had a script here, and it was written by her own mum.
Not only does it feature a top performance from Knightley (who shows she can also belt out a tune), but it is also further proof that Sienna Miller is a genuine talent (tabloid interest in the actresses often overshadows their genuine ability.)
Not every element of the movie quite gels (it never truly gets under the skin of Dylan Thomas), but the central foursome keep things consistently compelling.
Worst: Domino (2005)
This patchy effort shows flashes of greatness, but never converts them into a satisfying movie.
Initially, the kinetic, irreverent style is a gas, with Tony Scott flash-editing the hell out of a Richard Kelly script, and Knightley rocks the right amount of attitude as the (sort-of) real-life bounty hunter.
The problem is it just becomes a bit tiresome at around the halfway mark. The visual and narrative tics keep the characters at arm's length, and the abundance of subplots derail any opportunity for investment.
A shame - it feels like there's a good movie in here fighting to get out.