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The Big Bang Theory writers did a great job, over the course of 12 seasons, of crafting immersive backstories for each of the main characters. By the time the show premiered its series finale, fans knew just about everything there was to know about Sheldon Cooper, Leonard Hofstadter, Raj Koothrappali, Howard Wolowitz,  Bernadette Rostenkowski, Amy Farrah Fowler, and Penny. Wait, a minute. Something is wrong there. That’s right, fans never learned Penny’s last name. Regardless of being billed third in the list of actors, Kaley Cuoco’s character is known only by her first name. So, why wasn’t Penny’s surname revealed? Was it purposeful, or did it happen by accident?

Penny’s mysterious surname was sort of an accident

Everything in The Big Bang Theory seemed pretty intentional. Eventually, everything seems to get explained, and one would assume a missing surname would have been purposeful, but apparently it wasn’t. Penny’s last name was just never written into the script, and it seemed to work out just fine.

Kaley Cuoco as Penny and Jim Parsons as Sheldon Cooper
Kaley Cuoco as Penny and Jim Parsons as Sheldon Cooper | Cliff Lipsonl/CBS via Getty Images

The lack of surname may have something to do with the late rewrite of Penny’s character. According to Newsweek, Penny’s character was added to the show after test audiences found the original female lead to be a little too hardened for the nerdy guys next door. Initially, the team behind The Big Bang Theory had cast Amanda Walsh to play Katie, a department store clerk who is street smart and highly sexual. Test audiences apparently hated it, sending the executive team back to the drawing board.

Penny was the answer. She was still sexy but also embodied the bubbly naivety needed to balance out Sheldon and Leonard, as well as the rest of the cast. It’s possible that the quick rewrite caused writers to forget to give Penny a last name. Chuck Lorre, at one point, suggested Penny’s last name was Barrington, but fans never got to see that written into a script.

Superstition helped fuel the mystery

Apparently, superstitious producers helped further fuel the secret. According to Screenrant, Penny’s lack of a surname was a simple oversight, but by the time anyone noticed, it felt too late to give her one. Steve Molaro revealed that writers suddenly became superstitious about writing in a last name for Penny as if giving her a full name would somehow shift the dynamic of the show, however unintentional her singular name was.

It also seems like by the time Penny’s name, or lack thereof, became a point of contention, there really was no natural way to reveal it. Theoretically, it could have been written in when Penny and Leonard got married, but that would have seemed a little tired. It could have been revealed in the final episode, but that may have been too climactic.

It’s not like Penny’s last name was a big deal in the show. Unlike New Girl’s Schmidt, no one seemed to notice that Penny’s surname is not known. Offering up a big reveal would have felt somewhat disingenuous. So,  just Penny, she’ll remain in the annals of television history.

Fans can assume her last name is Hofstadter now

Penny and Leonard, after much back and forth, eventually end up married. Their relationship was an important storyline throughout the series, and their marriage was equally important. While fans may never know what Penny’s last name was supposed to be, everyone can assume she’s now a Hofstadter.

Johnny Galecki, who played Leonard, seems content with the idea that Penny took his last name when they finally tied the knot. A bit old-fashioned, sure, but it seems fitting for a couple who experienced so many bumps in the road. Penny Hofstadter does have a ring to it.

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