It's hard to imagine Dwayne 'The Rock' Johnson and Chris 'Thunder from Down Under' Hemsworth as anything other than mega-jacked man-mountains. However, before they were hitting the gym day after day, eating protein bars in their sleep, they were actually living relatively normal childhoods.

Such is the case for plenty of actors who make their on-screen debuts early into adulthood. At the other half of the spectrum, we've got the young prodigies, the kids who were thrust into acting (by parents or by pure passion) at the age when most are learning how to ride a bike.

We all know that the likes of Lindsay Lohan, Macaulay Culkin, and Dakota Fanning were child acting stars booming with talent, but did you know about these others?

20 Ryan Reynolds

These days we might know Blake Lively's hubby as the star of action films like Deadpool, Green Lantern, and The Hitman's Bodyguard, as well as romcoms like The Proposal, however, before all of that he was actually turning heads as a child acting prodigy. His career kicked off in the Canadian teen soap opera, Hillside.

19 Josh Hutcherson

From a young age, the talented Josh Hutcherson appeared in a number of TV commercials as well as minor film and television roles, but it wasn't until he landed his first big-time role in House Blend (TV pilot) that he started to shoot into stardom. RV and Zathura followed not too shortly after, and the rest is history.

18 Neil Patrick Harris

Believe it or not, NPH hasn't always been the on-screen ladies' man that we've seen in the form of Barney Stinson. In fact, the How I Met Your Mother star actually earned himself a Golden Globe nomination for his performance as a young actor in Clara's Heart, which was a 1988 feature by Whoopi Goldberg.

17 Alex Pettyfer

Although Alex wasn't the youngest of actors on this list when he started off, he was still just a teenager. While we know him mostly for his roles in I Am Number Four and Magic Mike, prior to that, he actually kicked off his on-screen journey in the TV-film, Tom Brown's Schooldays in 2005.

16 Scarlett Johansson

We might know ScarJo for her impressive performances as Black Widow in the MCU and for main roles in feature films like Lucy and Her, however, this household actress' timeline actually going back to the tender age of 9. Before she'd even started high school, her IMDB page had already begun to be populated.

15 Jennifer Lawrence

Long before this Hollywood sweetheart was turning heads in films like The Hunger Games and Passengers, Jennifer Lawrence was gaining experience on the small screen as a regular on the TBS sitcom, The Bill Engvall Show. From then, her career has skyrocketed, and there's still plenty more to be seen from here on.

14 Joseph Gordon-Levitt

While many people assume that Joseph Gordon-Levitt got his big break when 3rd Rock from the Sun aired on NBC in the late 1990s, he actually had amassed an impressive amount of IMDB credits even before then. Pictured above, for example, was his 1994 appearance alongside Danny Glover in Angels in the Outfield.

13 Joaquin Phoenix

When starting out as a child acting prodigy, before he was even allowed to drive a car, young Phoenix was putting his name out there for the world of Hollywood to see. These days, he's progressed tenfold and has become known for his roles in films like Gladiator and Her (pictured below), however, his young self in 1986's SpaceCamp (above) is still adorable.

12 Elijah Wood

Macaulay Culkin might be one of the most famous child actors of all time, however, few people realise that Elijah Wood actually stared alongside Culkin in The Good Son, a psychological thriller from 1993. It might not have carried as much as Lord of the Rings but it still put him on the map.

11 Amanda Seyfried

Believe it or not but the talented Amanda Seyfried actually has more on her resume than merely the cult classic Mean Girls and the Mamma Mia installments. As a young teenager, Amanda had landed recurring roles on a couple of TV soap operas -  As the World Turns as Lucy Montgomery, followed by All My Children as Joni Stafford

10 Felicity Jones

Today, when we hear the name Felicity Jones, our minds head straight to the recent Star Wars installments and the film adaptation of the Dan Brown bestseller, Inferno.  Long before those, however, this talented, Oscar-nominated actress was showing off her on-screen skills in The Treasure Seekers and The Worst Witch, and the tender age of 12.

9 Kirsten Dunst

These days we're all too familiar with the name Kirsten Dunst. On the flip-side, back in 1994 when she appeared, as a child of 11 years, alongside monumental names like Tom Cruise and Brad Pitt, she was just a drop in the ocean. She took the opportunity to play a vampire and seized it, catapulting her toward the top of the industry.

8 Natalie Portman

As soon as a young Natalie Portman showed her talent on the big screen it was clear that she was destined for greatness in the industry. And alas, that's exactly what happened - Natalie has gone from playing a 12-year-old girl by the name of Mathilda, in 1994's Léon: The Professional, to a beloved Oscar-winner.

7 Jodie Foster

It didn't take long for a young Jodie Foster to make a name for herself in Hollywood. At just 14 years of age, she had already made appearances in a number of TV shows and films. Of course, we'll never forget her Oscar-nominated portrayal of Iris in the infamous '76 crime drama, Taxi Driver.

6 Christian Bale

Christian Bale is renown for his roles as Batman / Bruce Wayne in The Dark Knight series, as well as his unique ability to transform his body in order to adapt to various roles. What many people don't realise, however, is that his acting career kicked off at a young age, with a repertoire that included starring in a Steven Spielberg-directed 1987 World War II drama

5 Jake Gyllenhaal

Before Jake Gyllenhaal worked his way up the ranks to become a household name thanks to roles in The Day After Tomorrow, Bubble Boy, and Love and Other Drugs, he was actually showing off his talents on the big screen in as Billy Crystal's son in the 1991 film, City Slickers. Clearly, since then, the only way was up.

4 Kate Winslet

Long before Kate Winslet brought tears to our eyes with her portrayal of Rose alongside Leonardo DiCaprio in the James Cameron iconic film, Titanic, she was showing off her potential on a handful of British TV shows.  It's fair to say that our beloved Kate made the transition to the big-time seamlessly.

3 Reese Witherspoon

We might know the lovely Reese Witherspoon for her role as a Chihuahua-wielding sorority queen Elle Woods in Legally Blonde, among a plethora of other rom-coms, however, her resume is jam-packed with much more content from days gone by. The Hollywood star actually began her journey way back in 1991, with a young role in The Man in the Moon.

2 Shailene Woodley

Here we are, folks - yet another Hollywood star who, surprisingly, started off from a very young age. Before Shailene made a name for herself on the O.C, she had already accrued a handful of movie credits, including a vital role in the 2005 period drama, Felicity: An American Girl Adventure.

1 Ryan Gosling

In today's entertainment world, there is perhaps no face nor name more recognisable then Ryan Gosling. From The Notebook to Crazy, Stupid, Love and Drive, Ryan's created an impressive list of acting credits, to say the least. It all started with a part in the Mickey Mouse Club. Any guesses who the guy next to him is? (hint: Seniorita)