The Big Bang Theory, initially centered around Sheldon and Leonard, almost didn't include the character of Bernadette, played by Melissa Rauch. Originally conceived as a guest role, Bernadette was introduced as one of Penny's co-workers at The Cheesecake Factory in season 3. However, due to her great dynamic with Penny and chemistry with the rest of the cast, CBS recognized her potential and promoted her to a series regular in season 4.

While Bernadette may not have received as much fanfare as the original cast members or Mayim Bialik's Amy, her addition to the show was crucial. She played an integral role in addressing the problematic portrayal of Howard's character during the early seasons.

Before Bernadette, Howard was depicted as sleazy and often made inappropriate advances toward women. However, his relationship with Bernadette led to significant character growth and a shift away from his playboy behavior. Their traditional romance allowed Howard to develop into a more respectful and committed partner.

Bernadette's impact extended beyond just Howard's character development. Her presence influenced the storylines of other characters as well. For instance, without Bernadette introducing Penny to the pharmaceutical industry, Penny wouldn't have had a successful career change from acting to becoming a pharmaceutical representative.

Additionally, Bernadette's involvement with Howard gave him less time to spend with Raj, potentially altering their friendship dynamics and even changing the possibility of a romantic relationship between them, which was subtly hinted throughout the series.

In summary, the inclusion of Bernadette as a regular character on The Big Bang Theory was a significant decision that positively influenced the show. Her arrival allowed for the course correction of Howard's character and provided him with a more meaningful storyline centered around love, marriage, and family. Furthermore, Bernadette's impact on other characters and their arcs cannot be overlooked, making her an essential addition to the ensemble cast of the beloved sitcom.