CBS struck gold with The Big Bang Theory, however, as we're going to reveal in the following, there were no guarantees for the sitcom at the start. Behind the scenes, the script underwent several changes, while numerous auditions took place. Even some of the main cast members didn't think the show was going to be made based on all the creative changes to take place at the start.

In the following, we're going to take a look at the audition process, and why things didn't start off in a promising direction. We'll also reveal how Brie Larson got implicated into The Big Bang Theory, and how she almost got cast in a role.

Larson herself revealed why she didn't get the role, and was praised by fans for her transparency.

The Big Bang Theory Audition Process Was A Nightmare At The Start

Early on, auditioning for The Big Bang Theory wasn't as glamorous as the show turned out to be. In fact, those behind the scenes kept changing up plotlines and casting ideas at the start. Simon Helberg himself revealed that when he got contacted for the series a second time, he hesitated given that he didn't think the show would follow through.

The same held true for certain characters. Penny wasn't casted, and instead, Katie was among the main characters alongside Sheldon and Leonard. However, given how poorly Katie tested, Bill Prady and company made the major cut.

"In the first pilot, the female character (who, at that point, was named Katie) is kind of rough," Prady tells EW.

"They hated her, but what was amazing was that they were defending Leonard and Sheldon so much," Prady added.

Kaley Cuoco was later contacted for a new role of Penny. It is said that Cuoco's team struggled with the decision given that they feared her character would be a secondary one on the show.

The Big Bang Theory team themselves revealed Penny was underwritten at the start, but in time, that all changed.

Cuoco herself had a positive experience at the auditions. She revealed, "I remember sitting next to Jim in the waiting room and he had a Blackberry," Kaley tells THR.

"It was an older phone and I remember introducing myself to him. He said he couldn't get his Blackberry working and was talking to it. I thought, "This guy would be a hilarious Sheldon." It might have been a Nextel, I don't know what it was!"

Cuoco got the role but in truth, there were a few major names that got turned down for the series.

Brie Larson Screen-Tested For The Big Bang Theory But Didn't Get The Role Because Of Her Age

There were more than a few major names that auditioned for the sitcom. Despite the changing script at the start, the fact that Chuck Lorre was implicated gave a lot of actors hope that the series would actually get the green light and air.

Marissa Tomei was a major name to audition for the show. Another surprising name to audition, none other than Brie Larson.

Looking at Brie's body of work, fans are no doubt interested in the possibility of Larson having joined the show - even if it was for a minor cameo like so many other big stars.

It is unclear which role Larson tried out for, however, she did reveal to doing a screen-test, but was unable to secure a role because of her age.

"I tested for The Big Bang Theory, I remembered that this morning. They were really sweet, they just said I was too young; it's true."

Given that Penny was the only major female character at the start of the sitcom, most assume Larson auditioned for Cuoco's role. However, there's also the possibility of Larson auditioning for the role of Katie. Either way, it would've caused lots of intrigue seeing Larson in such a spot. Nonetheless, her career turned out just fine, and probably even better.

Brie Larson Was Praised For Revealing The Stories Of Her Failed Auditions In The Past

Over on YouTube, Brie Larson has over 674K subscribers. Despite her hectic schedule, Larson has found a way to post life-related videos on YouTube, as fans get to see a closer look at the star.

Among her most popular videos, includes the struggles of going through an audition. Despite her success, Larson was praised for giving candid advice about her failures early on.

One fan wrote on YouTube, "It's nice to have an actor on YouTube talk about these things that only actors can talk about.

Brie does contribute to the YouTube community and provides us with information like this so I really don't understand the hate. I hope your channel continues to grow Brie."

Another fan comments, "This is refreshing. You never hear about these kind of stories. It's also inspiring because it shows that dedication pays off. Chase your dreams and don't give up."

Larson clearly helped lots of fans and aspiring actors with her stories from the past.