The Big Bang Theory had an entirely different title before its debut in 2007. CBS' popular nerdy show wrapped its 12-season run last May shortly after becoming the longest-running multi-camera show. Starting with only five main characters - Sheldon (Jim Parsons), Leonard (Johnny Galecki), Penny (Kaley Cuoco), Howard (Simon Helberg) and Raj (Kunal Nayyar) - the series brought in Bernadette (Melissa Rauch) and Amy (Mayim Bialik) as regulars by season 4.
As an ensemble sitcom, The Big Bang Theory was derived from its namesake hypothesis, which is the leading scientific explanation for the beginning of the universe, which is also the reason why its opening theme traces all major Earth events since its inception. Countless episodes of the show are devoted to the projects and experiments the central scientist characters are working on. Penny, on the other hand, was considered an outsider since she was working towards becoming an actress, making her the audience's viewpoint whenever the gang gets all nerdy together.
The Big Bang Theory wasn't always the sitcom's title, however. The Chuck Lorre- and Bill Prady-created project was originally going to be named after its main three leads: Lenny, Penny, and Kenny. If you're wondering who Kenny is, that was Sheldon's original name before the title was altered and he was no longer beholden to a rhyme scheme. Similarly, Leonard was saved from being called Lenny.
Lenny, Penny, and Kenny would have put the hit CBS show in the same category as other sitcoms titled after their lead characters, like Mork and Mindy, I Love Lucy, Seinfeld, Roseanne, Ellen - and yes, even the currently running The Big Bang Theory spin-off Young Sheldon. It's unclear what prompted the title change, but it's safe to assume that it may have something to do with the decision to use the name Sheldon for Parsons's character instead of Kenny.
Whatever the real reason was for The Big Bang Theory to change its title from Lenny, Penny and Kenny, it was a wise move by the show's creatives. There's nothing wrong with using character names on show titles - a lot of sitcoms that went this route became huge hits. All that being said, it's objectively terrible and corny, and doesn't really represent the unique premise of the series being a sitcom that's rooted in science. Instead, it simply sounded like a contemporary take on the classic Three's Company.
On top of that, Lenny, Penny, and Kenny also sidelines The Big Bang Theory's other two original characters, Howard and Raj, and then eventually Bernadette and Amy. Technically, The Big Bang Theory typically put more focus on Leonard, Penny and Sheldon, but much of the show's appeal in the long run came from the overall chemistry of all seven characters. And it was that chemistry, along with show's nerd culture comedy, that made The Big Bang Theory a success.