Marisa Tomei , Elizabeth Berkley , and Tara Reid all auditioned for the role of centime .

Somehow, it’s been 16 whole years sinceThe Big Bang Theorypremiered in September 2007. To celebrate the anniversary, here are 16 facts about the show that’ll surprise you, educate you, and honestly just make you want to do another rewatch:

1.The character of Penny wasoriginallygoing to be called Katie, and she wasn’t going to be the “bubbly” version of the character we know now, but a much more cynical character.Kaley Cuocoauditioned for the role, but originally it went to Amanda Walsh, who even filmed the original unaired pilot in 2006.

2.Marisa Tomei,Tara Reid, and Elizabeth Berkley alsoall readfor the role of “Katie” (aka Penny) before she was ultimately immortalized by the one and only Kaley Cuoco.

3.A long-discussed element of the show was that Penny never had a last name. The writers ultimately decided not to give her a surname before marriage because they got “superstitious” about it. Ultimately, her last name will always be her married name: Hofstadter.

4.Penny wasn’t the only role that could have looked super different — the role of Howard Wolowitz was actuallyoriginally writtenfor Kevin Sussman (who ultimately played Stuart), but ABC wouldn’t release him from hisUgly Bettycontract in order to free him up to play the role.

5.The characters of Sheldon and Leonard were named after producer Sheldon Leonard, who produced shows likeThe Andy Griffith ShowandThe Dick Van DykeShow.

6.And the character of Sheldon wasinspiredby a computer programmer whom Prady once worked with, noting that this programmer could “do amazing calculations in his head but couldn’t manage to tip the waiters in a restaurant,” according to NPR.

7.The origin story of Sheldon’s famous catchphrase “Bazinga!” is actuallyrevealedin a 2018 episode ofYoung Sheldon. As a boy, Sheldon was trying to act more childlike and frivolous, which led him to a comic book store selling funny toys by a brand called Bazinga — and the rest was history.

8.Young Sheldonalso reveals that Amy and Sheldon eventually have a son together — and they name him Leonard.

9.Kunal Nayyar has naturally curly hair, so he straightened his hair for every episode to play Raj.

10.Carrie Fisher and James Earl Jones met for the first time appearing as guest stars on the show, despite their history starring inStar Wars.

11.Meanwhile, Mark Hamill was “a little nervous” at first to commit to appearing in the Season 11 finale to officiate Sheldon and Amy’s wedding because the producers approached him as their “dream guest” without even having a script.

12.Mayim Bialik actually has a PhD in neuroscience in real life, and she hassharedhow it “came in handy” working on the show and how she would occasionally give small corrections to the scientific jargon in the dialogue. In fact, the writers even made Amy work in neuroscience as well because they figured it would make the character super accurate.

13.Melissa Rauch revealed that the reason Bernadette’s speaking voice was so high is that it was actually inspired by her mother in real life.

14.“Soft Kitty” is such a big part ofThe Big Bang Theory, but CBS and Warner Bros. were actually sued over it. The suit wasultimately dropped.

15.As an act of solidarity, Jim Parsons, Johnny Galecki, Simon Helberg, Cuoco, and Nayyar each took a $100,000pay cutfrom their notable $1 million–per–episode paychecks just before Season 11 to help elevate Bialik’s and Rauch’s salaries to over $425,000 per episode.

16.Finally, the show wasn’talwaysgoing to be calledThe Big Bang Theory —the originalworking titlewasLenny, Penny,and Kenny.

Amanda Walsh playing Katie opposite Johnny Galecki in the unaired pilot

Marisa, Tara, and Elizabeth from 2007

Penny and Leonard in a scene from an early episode of the big bang theory

Penny and Stuart in a scene on The Big Bang Theory season 2

A photo of producer Sheldon Leonard side by side with the characters of Leonard and Sheldon

Sheldon on a computer during a Big Bang Theory scene

Bazinga toy company from Young Sheldon

Amy and Sheldon in bed together

Raj and Howard in a scene in The Big Bang Theory

Carrie Fisher, James Earl Jones, and Jim Parsons on The Big Bang Theory

Mark Hamill on The Big Bang Theory

Mayim and Jim Parsons in a scene in the living room on The Big Bang Theory

Bernadette and Howard in a scene

Penny singing soft kitty to sheldon

The Big Bang Theory cast at the People's Choice Awards

Penny, Leonard, and Sheldon on The Big Bang Theory