Fans left ‘shaken to the core’ after realising how old Keira Knightley was in Pirates Of The Caribbean

I know they say 'start them young', but Keira Knightley might have taken that phrase a bit too literally.

The London-born star, 39, got bit by the acting bug not long after she'd left nappies behind and demanded an agent when she was just three-years-old - however, she had to wait until she was six until her wish came true.

She started to gain small parts in TV dramas as well as amateur productions under the guide of her stage actor parents Will Knightley and Sharman Macdonald, at an age where most people were more interested in playground drama.

Knightley landed the role of Natalie Portman's double in Star Wars: Episode I – The Phantom Menace when she was just 12-years-old, which marked her elevation into more major projects.

From there, she was cast in the Disney flick Princess of Thieves which was released in 2001 as she turned 16, while she also bagged roles in The Hole, Doctor Zhivago, Pure and Bend It Like Beckham.

As you can see, Knightley's teenage years were chock-a-block with acting gigs rather than the activities of a typical British teenager, so you'd think that we'd all have registered the fact she was a lot younger than we thought by now.

But that is apparently not the case - as social media users have been losing their minds after discovering how old the Pride & Prejudice star was when she secured her breakout role in Pirates of the Caribbean in 2003.

One film fan said on X: "Keira Knightley being like 17 when she filmed Pirates of the Caribbean shakes me to my core."

People can't believe how old Keira Knightley was in the first Pirates of the Caribbean film (Stephane Cardinale - Corbis/Corbis via Getty Images)

Another wrote: "This really just impresses upon me how f**king talented she is as an actress. Like god damn girl you haven’t even been alive long enough to have this type of range."

A third added: "She looked 25 at 17 and stayed looking 25 to this very day."

While a fourth chimed in: "I've never been able to watch it the same one I learned that. My brain is constantly going, 'she's 17!!' And then I think about what I was doing at 17....or 35."

If you haven't clicked on just yet, Knightley was just 17-years-old when she starred as Elizabeth Swann alongside Johnny Depp and Orlando Bloom in Pirates of the Caribbean: The Curse of the Black Pearl.

And although you might think this would be a teenage dream come true, the Brit revealed that the reality of the overnight fame she acquired off the back of the first film in the legendary franchise wasn't all that it's cracked up to be.

Knightley explained that she underwent 'many years of therapy' to deal with her meteoric rise to success, which she described as 'pretty horrific'.

She was just 17-years-old while starring alongside Orlando Bloom and Johnny Depp in the 2003 blockbuster (Disney)

Discussing her struggles in a 2018 interview with Variety, she explained: "I’m not an extrovert, so I found that level of scrutiny and that level of fame really hard.

"It was an age where you are becoming, you haven’t become, and you need to make mistakes," she said.

"It’s a very precarious age, particularly for women. You’re in some ways still a child. It was traumatic, but it set up the rest of my career."

Knightley also addressed how Pirates of the Caribbean catapulted her into the spotlight in 2019 during an interview with The Telegraph, explaining she suffered a mental breakdown at 22 following it's release and her fame from Love Actually.

She was diagnosed with post-traumatic stress disorder (PTSD) and was forced to take a year off to recuperate, which encouraged her to step away from mainstream movie gigs.

Knightley said she went through 'many years of therapy'. (Buena Vista Pictures)

"I knew I didn’t want to do big-budget films any more, because the fame that came with them I just couldn’t handle," Knightley said, while saying smaller roles gave her a 'level of fame that's much less intense'.

"If I was presented with the script for Pirates of the Caribbean today, I’d be wrong to do so, but I’d probably say no," she added - which suggests she isn't down to take part in the reboot that's been confirmed by producer Jerry Bruckheimer.

She also said that she 'really, really, really hopes' that her two young daughters Edie and Delilah - who she shares with her husband James Righton - don't want to follow in her footsteps and get into acting.