Big Bang Theory launched in 2007 as a show about four “nerds” and their hot but goofy neighbor. By the time it left a decade later, it had become a smart, socially relevant blockbuster and one of the greatest sitcoms of our time, dealing with intimacy, consent, motherhood, marriage and money. For the show’s 15th anniversary oral history, I conducted 120 hours of new interviews with creators, actors, producers and more, including Kaley Cuoco and Johnny Galeckiwho here speak candidly, sometimes tearfully — and for the first time in significant detail — about their off-screen and on-screen love story.
Cuoco and Galecki’s characters, Penny and Leonard, eventually married and had at least one child that we know of. The actors didn’t, of course, but they dated exclusively for two years, from 2008 to 2010. In fact, much of the authenticity of their on-screen relationship was driven by the love and respect that Cuoco and Galecki shared in real life. And when the off-screen relationship ended, their professional commitments and even their TV dialogue helped them heal. They develop a friendship that runs deep – and in many ways is the true love story of the series. Three plus years later Big Bang packed production, the duo is as tight as ever, as made evident by the many zooms they did together for this book to pay homage to Penny and Leonard—and each other. Below, excerpts from chapter u The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series.
Kaley Cuoco: I think a lot of what made Leonard and Penny work so well was my off-camera relationship with Johnny, which turned into such a sarcastic joke that bled into Penny and Leonard. Johnny and I’s relationship, in a way, mimicked Penny and Leonard. They were always messing with each other, and Johnny and I have a similar relationship – which you do after years together. We’ve always had each other’s backs, and you can’t lose that. And I think that happened on screen. He made our relationship funny and endearing.
Although Cuoco and Galecki were the most famous stars thanks to 8 Simple Rules and Roseanne, respectively, when Big Bang launched, the two did not know each other. But when they met, there was an immediate connection — and for Kuok, a desire for something more.
Kaley Cuoco: I had a big crush on Johnny early on. I didn’t even hide it. He has such swagger. We were both dating people at the time, but I only had eyes for Johnny. Then when I found out he had eyes for me too, I thought, Uh‑oh, this is going to be trouble.
Johnny Galecki: I have a healthy ego, but you really have to hit me over the head to tell me you’re flirting with me. I had no idea of any kind of crush before Kaylee and I started dating.
From the beginning, the script called for Leonard to fall in love with Penny, declaring that their babies would be “smart and beautiful.” On paper, it was never meant to work — she was a beautiful, naïve, aspiring actress from Nebraska; he was a brilliant experimental physicist without the swagger, mommy issues, and lack of confidence. But it was also a draw — two people from different worlds with an intrigue for each other (in fairness, more so than Leonard than Penny, at least at first). It’s a classic formula that, when done right, can work so well. From Ross and Rachel to Sam and Diana to Tony and Angela, Penny and Leonard had the same potential, which became apparent in the series’ sixth episode—”The Middle Earth Paradigm”—when a drunken Penny, dressed as a hottie, kisses Leonard on her Halloween party after her ex-boyfriend shows up. It was technically the first kiss for both Kuok and Galecki.