TBBT's Penny Wasn't Supposed to Have a Last Name—Until This Happened

Not a secret one, not a middle initial, not even a one-off throwaway. Just "Penny." Meanwhile, every guy on that couch had full names, full backstories, and full résumés. Penny? She was just lucky to get mail.

And then the props department went rogue.

In a season 2 episode titled The Work Song Nanocluster, Penny gets a package. Harmless, right? Except eagle-eyed fans paused the scene and noticed the label said "Penny Teller." That kicked off years of fan speculation that this was her real name. It wasn't.

Turns out, the label wasn't part of any master plan. It was just a prop guy trying to make his fake mail look legit.

Here's what actually happened:

• Scott London, head of props, needed a name for a shipping label.
• He asked someone — possibly co-creator Bill Prady — what to use.
• Someone offhandedly said "Teller" (as in, yes, Penn & Teller) and assumed no one would notice.
• They were wrong.

London explained:

"I had to put a last name on the label or the driver's license. I mean, you can't just tell me to ship to Penny with no last name!"

Prady later clarified:

"Emphatically, Penny's last name is not Teller. I was told it would be blurred out. It wasn't. But no, it's not canon."

Even Kaley Cuoco got in on the retrospective chaos:

"Scott London was so brilliant. He really took it seriously and had no idea this would be such a thing."

Co-star Jim Parsons joked about the absurdity of it all:

"She's not Prince or Madonna! She's a normal girl in Pasadena named Penny something."

Apparently, it became an unspoken rule in the writers' room not to give her a last name — even after she married Leonard. As showrunner Steve Molaro put it:

"We made sure to edit around even hearing what her last name would be. Her driver's license isn't even accurate."

By the time it became a running gag, fixing it would've felt weirder than just leaving it. And Cuoco? She was fine with that:

"No, I kind of love that it was just Penny, and then Penny Hofstadter, which I thought was so cute."

So no, her name isn't Teller. It never was. The internet just latched onto a background detail like it always does, and the showrunners decided to lean into the mystery instead of retcon it.

Penny had no surname for nine seasons because nobody in charge could agree on one — until she married Leonard and finally inherited a full identity through matrimony. Naturally.

You can watch her go from "just Penny" to "Penny Hofstadter" on The Big Bang Theory, now streaming on Max.