Like some of the actors of this list, The Big Bang Theory got better with age. While the show got some mixed reviews in earlier seasons, the last several seasons were among their best. The show originally focused on five characters: Penny, Sheldon Cooper, Leonard Hofstadter, Howard Wolowitz and Raj Koothrappali. Although, several more season regulars were added by the show's finale including Howard’s wife Bernadette and Sheldon’s wife Amy.

The Big Bang Theory ran for 12 seasons, which is long for any show. The actors hired for season one look totally different after shooting for so many years. While some look like they haven’t aged a day, there are others who are definitely showing their age. Here are 15 pictures of the cast from season 1 to season 12.

15 Penny Gets Better With Age

Kaley Cuoco started playing Penny when she was just 22 years old. So even after the 12 seasons of The Big Bang Theory, she was still only 34 years old. This might be one of the reasons why Kaley still looks so amazing. Either way, it looks like Kaley just gets better with age.

14 Sheldon Discovered A Way Not To Age

While Sheldon Cooper is 27 years old during the first season of The Big Bang Theory, Jim Parsons was 34 years old. Even after playing Sheldon for 12 seasons, Jim looks great. Especially for a 46 year old. It makes me wonder if Sheldon Cooper secretly discovered a way to stop aging.

13 Leonard Is Looking His Age

While Sheldon and Leonard were both 27 years old in the first season, the actors who play them are a couple years apart. Johnny Galecki was 32 years old when the show started, and he ended the show when he was 44 years old. Even though Johnny began the show looking great, he definitely started to look his actual age toward the end of the show.

12 Howard's Hair Cut Gets An Upgrade

Both Simon Helberg and his character, Howard Wolowitz, are about the same age. He started the show when he was 27 years old and ended it at 39 years old. Simon Helberg definitely got older but it wasn’t all bad. One of the biggest differences is an upgrade in his hair style, and it was long overdue.

11 Raj Ages Like Fine Wine

Rajesh Koothrappali is played by Kunal Nayyar, who was 26 years old during season one. Raj got teased a lot for his use of “girly” beauty products, but apparently he was onto something. In the 12 seasons of the show, it looks like Raj only aged about half of that.

10 Maturity Looks Amazing On Bernadette

Bernadette Rostenkowski-Wolowitz was introduced to The Big Bang Theory during season three, and became a regular on season four when she got engaged to Howard. Melissa Rauch was 29 years old when she started playing Bernadette. While she always looked gorgeous, she seemed to only look better as the show continued.

9 Amy Keeps Her Grandma Wardrobe

Dr. Amy Farrah Fowler made her first appearance on season three of The Big Bang Theory as Sheldon’s friend that’s a girl, although her fashion choices left something to be desired. Mayim Bialik was 35 years old when she first appeared on the show. While Amy doesn’t look like she aged a lot, her wardrobe could use an update!

8 Stuart Doesn't Age Gracefully

Kevin Sussman played the role of Stuart Bloom, the owner of everyone’s favorite comic book store. Kevin was 39 years old when he first appeared on The Big Bang Theory. He is probably the one who ages the least gracefully. Although, Stuart is the oldest one in the group, so we guess he’s supposed to look a little older.

7 Mary Cooper Is The Ultimate Mom

Mary Cooper is your typical southern mom and everyone loves her for it. She was also the only one who could control Sheldon. Laurie Metcalf looked great for being 52 years old during the first season of The Big Bang Theory. And she just continued to be the ultimate mom for the remainder of the show.

6 Beverly Went Back In Time

Christine Baranski played the role of Beverly Hofstadter, the overly critical mother of Leonard. Christine looks absolutely amazing for being 57 years old when first appearing on The Big Bang Theory. However, what’s even more amazing is that she looks exactly the same at the end of the twelve seasons.

5 Barry Kripke Embraces His Older Age

John Ross Bowie played the role of Barry Kripke on The Big Bang Theory for 10 years. Kripke also worked at the university and was everyone’s favorite frenemy. John Ross Bowie was 48 years old when the show ended and he is another one who is definitely showing his age.

4 Wil Wheaton Ages At A Normal Rate

Wil Wheaton played himself on The Big Bang Theory for 10 years. He was somewhat of a celebrity on the show for playing Wesley Crusher on Star Trek, a show all the guys were obsessed with. Wil was 47 years old when the show ended, and he aged pretty well during the show.

3 Leslie Winkle Makes Older Look Good

Leslie Winkle was a fellow scientist at the university, as well as a love interest for several of the guys at different times during the show. Leslie was played by Sara Gilbert. She was 32 years old during the first season of The Big Bang Theory and even after 12 seasons, Sara still looked amazing!

2 Did Emily Actually Get Older?

Laura Spencer played the role of Emily Sweeney on The Big Bang Theory. Emily was one of Raj’s longest relationships on the show. After looking at the before and after pictures of Laura Spencer, you would think she hadn’t aged at all! Although, she was only on the show for a couple seasons, so it’s hard to tell.

1 Mr. Koothrappali

Mr. Koothrappali is a fun character on The Big Bang Theory, especially since he is mostly seen only on video chat when he called to chat with Raj. He is played by Brian George. I am thinking Sheldon also showed Mr. Koothrappali the trick to staying young, because he might look the best out of everyone!