See What 'The Big Bang Theory' Stars Looked Like in Season 1 vs. Season 12 | 22 Words

The Big Bang Theory finally came to an end after twelve long years.

Chuck Lorre and Bill Prady's beloved comedy follows a group of friends (and socially awkward nerds) as they navigate life. With a well-known ensemble cast, we have Leonard (Johnny Galecki) and Penny (Kaley Cuoco), Raj (Kunal Nayyar), Howard (Simon Helberg) and Sheldon (Jim Parsons).

The show premiered way back in 2007, when side-swept bangs, denim mini skirts, and low-rise jeans were all the rage. The cast was perfectly of-the-moment back in Season 1, but boy... do they look different now.

Come take a gander at what the stars looked like at the beginning vs. today, and then stay tuned to see what they look like when they're not playing their famous characters!

Sheldon — Season 1

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Sheldon was a child prodigy (which we see in the show's spinoff series Young Sheldon) who started college when he was only 11 years old. He earned a PhD when he was 16. Now, he's a theoretical physicist who researches quantum mechanics and string theory. Even though he has a super high IQ, he's socially awkeard and finds most social interactions difficult to handle. Sheldon often brags about how smart he is at inopportune times and fights to have things his way, no matter what.

Sheldon — Season 12

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Later in the series, Sheldton begins a relationship with Amy Farrah Fowler, and they get married.

Penny — Season 1

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Penny is an aspiring actress from Omaha, Nebraska who moves in across the hall from Sheldon and Leonard and works as a waitress at the Cheesecake Factory. After realizing she's not making it as an actress, Penny becomes a pharmaceutical sales rep.

Penny — Season 12

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Over time, she makes friends with Bernadette and Amy, and they hang out in each other's apartments. As the show progresses, Penny and Leonard get together and eventually marry.

Leonard — Season 1

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Leonard is an experimental physicist with an IQ of 173. His claim to fame is that he got his PhD when he was only 24 years old. Leonard is a self-proclaimed nerd who loves Dungeons & Dragons and video games. He and Sheldon are roommates at an apartment in Pasadena, CA.

Leonard — Season 12

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At the beginning of the series, Leonard is head over heels for his hot new neighbor Penny. By the end of the series, the two get married.

Rajesh — Season 1

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Rajesh is a particle astrophysicist from India who has trouble talking to women. He owns a Yorkshire Terrier named Cinnamon. Rajesh gets mocked for being "feminine" and especially for taking on more of a womanly role in his friendship with Howard. Raj dates Lucy later in the series, who struggles with social anxiety as well, but the couple doesn't work out.

Rajesh — Season 12

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Rajesh eventually ends up dating Emily and they make their relationship exclusive.

Howard — Season 1

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Howard is an aerospace engineer with a Masters from MIT, but he doesn't have a doctorate, unlike Sheldon, Leonard, Rajesh, Bernadette and Amy. Howard trains as an astronaut and serves as a payload specialist. He thinks of himself as a ladies man, but eventually, he starts dating Bernadette and becomes a one-woman man.

Howard — Season 12

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Later in the series, Howard and Bernadette get engaged and then married. Howard spends too much money on toys and often fights with Bernadette because she makes so much more money than he does.

Over the years, the show's cast has revealed a lot about how they, and their characters, have grown.

First, there's Leonard.

Leonard has been in the core cast since the very beginning. He's definitely the least socially-challenged of his friends--though he still has his moments!

He's actually pretty lucky in love.

Again, he's at least the more experienced out of his friend group. And he's the long-suffering roommate of Sheldon, although he's really quite patient of all the shenanigans.

Leonard has changed a lot over the years.

He was smitten with Penny, the girl next door, almost immediately. They had a tumultuous relationship but finally tied the knot in season 9.

And John Galecki looks way different in real life.

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He'd been a working actor before The Big Bang Theory, but that's where his career really took off.

The character of Leonard has won him acclaim.

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Galecki has won numerous awards over his tenure on the show, including an Emmy for the leading role in a comedy television series.

Next up, Sheldon (and Jim Parsons).

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Sheldon has been a fan favorite pretty much since the show began airing. He's such an atypical character, with his Spock-like understanding of humor, empathy, and human interaction that fans can't help but be entertained.

But even Sheldon can find love.

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Since season 5, he's been in a relationship with Amy--whose extremely dry and literal view of the world rivals Sheldon's own.

And he's always good for a laugh.

And a catchphrase. I'm pretty sure people who don't even watch the show are aware of the term "Bazinga" on some level!

Jim Parsons is doing pretty well, too.

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Another actor who really launched his career off of Big Bang Theory, Jim Parsons is one of the highest-paid comedy actors in the industry right now.

Amy Farrah Fowler drops in right at the end of season 3.

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Sheldon's buddies Howard and Raj decide to find his perfect match via online dating. And who should the website's algorithm show them? Amy.

And she really is the perfect match.

She shares Sheldon's outlook on nearly everything, and she's a brilliant neurobiologist.

Then again, so is Mayim Bialik.

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Bialik plays the role of Amy, and though she's been acting for a long time (since the age of 12), she's also a neuroscientist IRL.

And she looks completely different outside of the show.

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She and Amy may share degrees (Amy's is a nod from the writers to Mayim's actual specialization), but they've got very different styles!

Howard Wolowitz has had quite the journey.

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From under his mother's thumb to outer space over the course of the show, Howard doesn't think small.

He's matured a lot.

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Howard got married to his paramour Bernadette in season 5, and the couple now has a daughter named Hallie.

He's an aerospace engineer.

Hence, his space travel. However, Howard's real challenge has been moving away from his mother, who never stopped treating him like her baby boy.

Simon Helberg has changed, too.

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First off, he doesn't make a habit of hanging on to Howard's bowl cut when he isn't filming.

He's also done more work outside TBBT.

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Helberg has joined other film and television projects, including the movie Florence Foster Jenkins. He's also married and has two kids with actress Jocelyn Towne.

Here's some Simon Helberg trivia:

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Did you know that Helberg is actually a black belt in karate? Howard may have been to space, but his real-life counterpart has some cool stuff, too.

And Raj is Howard's best friend.

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Another of the core cast, astrophysicist Rajesh Koothrappali is often with Howard--hanging out at Leonard and Sheldon's place.

Raj also has some anxieties.

At the beginning of the show, Raj was so anxious he couldn't even speak to women (sober, that is)! He's gotten over that fear as the show progressed though.

The actor who plays him, Kunal Nayyar, is a little different!

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Kunal is now 37 and doing quite well for himself; his foundation with TBBT has brought him other film and TV roles in the years since.

Also, he probably doesn't need alcohol to talk to his wife.

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Nayyar's wife, the Indian model Neha Kapur, and he got married in 2011.

Melissa Rauch is Bernadette Wolowitz.

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Penny first introduced Bernadette to Howard, during season 3 of the show. As it turns out, they have overbearing mothers in common, and quickly hit it off.

And here's Melissa Rauch on a non-acting day!

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Rauch joined the rest of the main cast for the final season of TBBT, but she's had other small roles before Bernadette. Did you know she'd been on The Office and Trueblood?

Leslie Winkle is Sheldon's eternal nemesis.

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She's written as the "female Leonard" and she had a relationship with Howard at one point, but no matter what, Leslie is in a feud with her scientific rival Sheldon.

I doubt actress Sara Gilbert shares that feud, though.

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Gilbert in real life is happily married to her wife Linda Perry and became famous for her role on Roseanne as Darlene Conner before TBBT came around.

And finally: Penny Hofstadter.

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Penny started out as the pretty blonde neighbor, but her character has developed a lot since then! She and Leonard also eventually married in Vegas.

Kaley Cuoco has been in TBBT since the beginning.

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And at only 33, she's done a lot in her time as a popular actress. Her sizeable Big Bang salary even enabled her to start her own production company! Share this story with other mega-fans of The Big Bang Theory!