'Big Bang Theory' Star Kaley Cuoco Shows How Much She has Changed Since Season 1

The Big Bang Theory just kicked off its twelfth and final season, and the cast has come a long way since the CBS sitcom debuted back in 2007.

Series star Kaley Cuoco illustrated that point on Instagram on Tuesday, sharing side-by-side photos of herself from the show's first season and its last.

The first snap finds the actress in one of her character Penny's early signature stomach-baring shirts and sleek blonde hair, while the second shot finds her in more comfortable clothing and sporting a wedding ring.

"We have come a long way from the pilot to tonight's season 12 premier .. don't miss our beginning of the end!" Cuoco wrote. "@bigbangtheory_cbs I look exactly the same, right?"

After the show's cancellation was announced, Cuoco used social media to reflect on her time on the series and express her sadness at its conclusion.

"This ride has been a dream come true and as life changing as it gets," she wrote on Instagram next to a photo of herself and her castmates. "No matter when it was going to end, my heart would have always been broken in two. Drowning in tears, we promise to bring you the best season yet. To the fans, our crew, families, Chuck Lorre, Warner Brothers, CBS, and everyone who has supported us for so many years, thank you. We are goin out with a bang."

Cuoco has made it clear that she would have been happy to continue the show, telling Extra that the cancellation has "broken my heart."

"I am so sad that it's ending," she said. "For the record, I would have done 20 more years."

The news was announced to the cast and crew by co-creator Chuck Lorre, with Cuoco recalling of the moment, "I was bad, but everyone was crying."

She also opened up about receiving the news during a recent appearance on The Late Late Show.

"It was definitely tough. There was not a dry eye in the room. A lot of hysterical sobs," the actress shared. "I think I wrote this on my social, it wouldn't have mattered when it ended, we all would've been completely devastated. So it's been a long run and we've been very grateful. It's time to, I guess, move on to other things, which is so heartbreaking, you know? But it would've been heartbreaking no matter when."

The Big Bang Theory airs Thursdays at 8 p.m. ET on CBS.

Photo Credit: Getty / CBS Photo Archive