Leonard Hofstadter and Penny were undoubtedly the most iconic couple on the hit sitcom, The Big Bang Theory. Johnny Galecki and Kaley Cuoco, who played the romantic characters, exhibited undeniable chemistry that could almost be mistaken as accurate. Also, the fact that Leonard and Penny weren't on each other's level, socially, intellectually, and financially, made them a fan-favorite for the 12 seasons the show lasted.
Related: Some 'Big Bang Theory' Fans Think Penny Loved Sheldon More Than Leonard
The on-screen lovebirds went through ups and downs in their relationship― including Leonard suffering at the hands of Penny's ex-boyfriends and Sheldon Cooper giving Penny a hard time when she moved in ― before they eventually walked down the aisle in season nine.
However, beyond the bond displayed on-screen, Galecki and Cuoco's love for one another translated into their real lives. Like life imitating art, the pair endured some challenges, especially with the end of their not-so-secret romantic relationship. Nevertheless, the co-stars managed to allow their genuine friendship always to shine through.
10 They Dated In Real Life
Unknown to many, Cuoco and Galecki dated off-screen. The colleagues were together for two years before they split in 2009. However, the pair kept their romance a secret, denying all rumors until 2010.
Cuoco, who dropped the bombshell, revealed that they never spoke about it and avoided going to places together because they were intent on protecting their on-screen romance. The 35-year-old shared that she first crushed on Galecki during the pilot, but he had a girlfriend at the time.
9 Their Romance Wasn't Fun
Although Galecki and Cuoco fought hard to keep their relationship under wraps and deeply loved each other, the actress later confessed that their romance didn't turn out to be as much fun as they both desired.
Cuoco admitted that the relationship wasn't what she pictured because they were always in hiding. She shared that she hated having to deny being in a relationship with Galecki, despite loving him, which eventually took a toll on both of them.
8 It Was Difficult To Film Intimate Scenes
Penny and Leonard's romance in the show began getting heated and serious when Galecki and Cuoco officially broke up. Although the pair never allowed their breakup to get in the way of their work, Cuoco admitted that filming sex scenes wasn't a walk in the park, saying:
"When we broke up, obviously, it was a little sensitive for a minute, but I remember those weeks that Chuck had written these episodes where all of a sudden our characters were, like, sleeping together every other second."
The actress teased that she believed co-creator Chuck Lorre was trying to mess with her and Galecki. However, she and Galecki managed to brilliantly come on top, making their intimate scenes look genuine.
7 Galecki Loves Celebrating Cuoco On Social Media
Galecki has often described Cuoco as a special part of his life, saying she isn't just an ex and a co-star. The actor never fails to back up his words with actions, as seen on his social media page.
When Cuoco tied the knot with her second husband Karl Cook in July 2018, Galecki attended the ceremony. He later took to Instagram, sharing two lovely images from the nuptials. Galecki uploaded a heartwarming portrait of him and Cuoco holding hands and, in the caption, confessed that he couldn't be happier for his fake wife.
6 Cuoco Praised Galecki's Parenting Skill
Galecki added a new title ― father ― to his resume when he and his now-ex-girlfriend Alaina Mayer welcomed their son, Avery, in December 2019. The Roseanne actor and Meyer first shared the news of the pregnancy in May 2019.
Months after her on-screen husband became a father, Cuoco gushed over him, revealing that Galecki has always wanted to have a child. She shared that they have a group chat, and Galecki sends her photos of little Avery. However, she hadn't met the newborn in person.
5 They Have Each Other's Back
Over the years, Cuoco and Galecki have gotten so close that their friendship has sometimes sparked rumors of an affair. When Cuoco filed for divorce from her first husband, Ryan Sweeting, in September 2015, there were speculations that Galecki was the reason. True to their playful nature, the best pals took to social media to shut down the rumors.
Cuoco uploaded a playful photo of her and Galecki fist bumping outdoors alongside a caption that read, "So sorry to disappoint, but no home wreckers or secret flings going on here. Me and @sanctionedjohnnygalecki are just the best of buds." Galecki posted a similar photo and, in the caption, reiterated Cuoco's message. It seems fans of The Big Bang Theory who hope to see them together would just have to settle for Penny and Leonard.
4 Friendly Pda Sessions
Although it has been more than a decade since Galecki and Cuoco called it quits, the pair continue to share cozy moments in public. At the 2016 People's Choice Award, the duo enjoyed a steamy dose of friendly PDA.
Cuco shared a heart-melting photo of her and Galecki enjoying a tight hug on the red carpet. In the caption, she noted that although Galecki was her date to the award show, they weren't dating.
3 Social Media Banter
Amid the touching friendship, Galecki and Cuoco have moments when they turn on each other. While giving a Valentine's Day tribute to Karl Cook in February 2021, Cuco wrote that she couldn't remember a moment before meeting Cook as her life was boring. It was suggested that she took a jab at her romance with Galecki.
Galecki, however, didn't take her confession lightly and took to the comments section of the post, writing, "um." Upon seeing her ex-boyfriend's comments, Cuoco couldn't help but laugh at how funny it was.
2 A Public Fight
Despite how hard Galecki and Cuoco tried to keep their relationship private, it's not inconceivable that sometimes when around their co-stars and the rest of the crew, they sometimes lowered their guard.
During the 2017 Comic-Con, the show's executive producer Steve Molaro recalled crashing in on a fight that the former lovebirds had during their first Comic-Con appearance in 2007. Molaro shared that the co-stars were arguing at a hotel bar and when Cuoco was about to cry, she sought comfort from him.
1 An Emotional Ending
After an eventful run, following 12 seasons and 279 episodes, The Big Bang Theory came to an end in May 2019. It was a heartbreaking moment not only for the die-hard fans but for the tight cast.
The duo was emotional about the show's end with Cuoco uploading an image of her crying during the last table read in April 2019. On the other hand, Galecki said in an interview, "none of us will be able to keep from crying during the last taping. We've got to justify it in the writing somehow, sensitive group."