The Big Bang Theory's Prop Department Gave Penny An Unauthorized Last Name

There's a pretty famous thing on "The Big Bang Theory" regarding Penny's last name — which is to say, she doesn't have one. Kaley Cuoco's bubbly, friendly, and gorgeous aspiring actress — who moves in across the hall from Sheldon Cooper (Jim Parsons) and Leonard Hofstadter (Johnny Galecki) in the show's pilot and becomes an indispensable part of their lives as a result — is just Penny for most of the series, though she takes Leonard's last name when the two get married in season 9 (and, I suppose, when they get married again in season 10). Still, we see packages meant for Penny and her driver's license on the show, and in Jessica Radloff's 2022 book "The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series," Scott London, the head of the show's props department, opened up about the time he put Penny's "last name" on a package for the sake of realism.

In the season 2 episode "The Work Song Nanocluster," Penny starts a business selling "Penny Blossoms," or little floral hair ornaments, out of her apartment and goes sort of insane in the process ... to the point where she unexpectedly gets an order of her own creations in the mail. Apparently, London went ahead and put the last name "Teller" on the package, and eagle-eyed fans spotted it, screenshotted it, and declared that her last name was Teller. (Yes, it does sound like Penn and Teller, the famous magic duo. Put a pin in that.)

"Props had to put a label on it and it happened to be on camera," writer and executive producer Steve Molaro explained (somewhat tersely) to Radloff in the book. "We didn't sanction it, we didn't write it, and we didn't intentionally put it there. It's fun to think about, sure, but we certainly never talked about it."

"It's amazing these producers don't communicate better. I think it was Bill Prady, because he's friends with Penn and Teller ... but I was told, 'make it Teller,' because I always say, 'What do you want for a last name?'" London recalled before saying that he typically just gave Penny his own surname. "For a while, I used my last name, London, as her last name just so there was something. But the only name I know that was given to me was Teller because I had to put a last name on the label or on the driver's license. I mean, you can't just tell me to ship to Penny with no last name!" Sorry, but London is right! That's how mail works!

Okay, so what really happened here? Bill Prady, who created the show alongside Chuck Lorre, may be able to explain it. "Scott said, 'I have to have a last name,' and I said, 'Will we ever be able to read it?' and he said, 'No.' And I said, 'All right, well, make sure it's Greeked out enough that you can't make it out.' And he said, 'What should I put there?' And I think I might have said 'Teller' because of Penn and Teller, Penny Teller. I think it might have amused me in the moment. But I had assurances it wasn't going to be seen, that Scott just needed it for the visual shape of the block of type.

"But, emphatically, Penny's last name is not Teller," Prady continued. "I don't know how that image of the shipping label exists and how fans were able to see it or make it out. It's like the roommate agreement — they had to fill pages with words. Prop people have to make things that will look real, but the intent is that you will not see them." (Prady has, apparently, not spent a ton of time on the internet, because fans of shows will take whatever blurry images they can find and create fan theories accordingly.)

"I do remember that shipping label!" Cuoco exclaimed, speaking to Jessica Radloff as well. "Scott London was so brilliant. He really took it seriously, and had no idea that this last name would be such a thing!" As for Jim Parsons, he just thought the whole thing was funny and just a tiny bit frustrating. "I mean, she's not Prince or Madonna! She's a normal girl in Pasadena named Penny something," Parsons joked. "But yes, very early on, I remember looking at the mail in a scene, and it said Penny London. We all found it amusing in a charming way that the prop master had given her his last name. It was just perfect, Scott. "

Still, like fans of the show, Parsons did start to wonder about why Penny never got her own last name. "And I'm such a curmudgeon, it's the kind of thing where I look back now and think, 'This really is so funny this went on.' I remember the time this was a whole topic of conversation and I was like, As if we don't have enough to think about, we gotta talk about superstition about giving her a goddamn last name!' But now I think it's fun."

At the risk of also sounding like a curmudgeon, it's weird and bad that Penny, who is the only lead female character on the show for three entire seasons, doesn't have a last name until she gets married. Her two companions and fellow female leads, Bernadette Rostenkowski-Wolowitz and Amy Farrah Fowler — played by Melissa Rauch and Mayim Bialik, respectively — get multiple last names, even! I can also see, though, that the longer it went on, the harder it was to remedy ... and it just became a joke. Anyway, as Steve Molaro told Jessica Radloff, even if she does have a maiden name — which she doesn't! — it's not Teller, so everybody can relax.

"Her last name being Teller is absolutely not canon," Molaro clarified. He went on:

"The canon is that she does not have a last name that we ever assigned to her, including us saying, 'I don't know, put Teller on the label.' Even though that happened, that does not mean it's her last name. We never decided to know what it is, and we're never going to make one. Even when she and Leonard got married, we made sure to edit around even hearing what her last name would be. And the driver's license that says her last name ... it's not even the right address or the right height, either."

"There were times I maybe had an idea what her last name actually was, but then it was almost weird for me to think she had a last name," Kaley Cuoco also said in the book. "She was just Penny." Thinking it over, Cuoco did reference one of Sheldon's most famous quirks — his three-knock system: "I think it was a fan who once said to me, 'Wouldn't it be funny if your name was Penny Penny Penny, and Sheldon knew the whole time and everyone just started doing the knock, and then later he was like, I knew that was your last name!'"

Ultimately, Cuoco was happy with her character's pointed namelessness. "But no, I kind of love that it was just Penny, and then Penny Hofstadter, which I thought was so cute," she said. In Radloff's book, we can see that her acting resumé says "Penny Penny" and her driver's license says Teller as her last name, but now we know: Teller is not her canonical last name. 

You can watch Penny's journey from "just Penny" to "Penny Hofstadter" on "The Big Bang Theory," which is streaming on Max now.