1 / 14
Jim Parsons (left) was a really sweet kid when he was young! This is him as a little boy with his mother and little sister Julie.
2 / 14
Here is the ever-famous Jim Parsons, also known as starring character "Sheldon Cooper" from 'The Big Bang Theory' today. He really grew up to be a handsome man.
3 / 14
Incredibly cute! This little girl is Melissa Rauch who we all know as "Bernadette Rostenkowski-Wolowitz" on The Big Bang Theory!
4 / 14
And here is the actress again, looking stunning at a red carpet appearance...!
5 / 14
Would you have been able to tell which Big Bang cast member the cute little girl on the left is?
6 / 14
... of course! It's Mayim Bialik, also known as "Amy Farrah Fowler"! Here she is at the Big Bang Theory finale party.
7 / 14
Who might that be on the right? The little boy hiding under a plastic bag at Niagara Falls is none other than...
8 / 14
... Johnny Galecki, who became world-famous in the role of "Leonard Hofstadter" on The Big Bang Theory.
9 / 14
Can you recognize which actress is posing with her little sister here?
10 / 14
That cheeky smile is unmistakable: It is, of course, Kaley Cuoco! Also known as "Penny" on The Big Bang Theory.
The Big Bang Theory is one of the most successful and popular sitcoms of all time and this is due, in large part, to the actors!
We all know and love the Big Bang cast, with stars including Johnny Galecki, Jim Parsons, Kaley Cuoco, and Simon Helberg. But would you recognize them as children?
Carry on reading to see what your favourite Big Bang Theory actors looked like as kids...