‘The Big Bang Theory’ finale fails to answer the show’s biggest mystery and the cast hints it’s one we’ll probably never learn

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“The Big Bang Theory” still has us wondering Penny’s last name after 12 seasons.
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Michael Yarish/CBS

“The Big Bang Theory” series finale gave us fans a few unexpected surprised, including a working elevator, but the CBS sitcom left one very important question unanswered.

What is Penny’s last name on the show?

Over the course of 12 seasons, fans have wondered whether or not the show would ever reveal Penny’s maiden name. Some were hoping we may finally learn it on the series finale, but the hour came and went without any revelation.

Some fans were left a bit disappointed and frustrated by the lack of closure.

The “Big Bang Theory” cast were later asked about the lingering question on a pre-taped episode of “The Late Show With Stephen Colbert.”

Kaley Cuoco, who has played Penny from the start, had a quick response.

“You’ll never know,” said Cuoco while sealing her lips shut.

Kaley Cuoco has nothing to reveal about Penny's last name.

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Kaley Cuoco has nothing to reveal about Penny’s last name.
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CBS

When pressed further by Colbert, Cuoco and Johnny Galecki, who played Penny’s husband Leonard, opened up a little bit more about the mystery surrounding Penny’s last name.

“You became suspicious about it after awhile,” said Galecki.

“There really is no answer,” said Cuoco, claiming Penny doesn’t have a last name. “She’s Cher.”

Kaley Cuoco suggests Penny is a one-word name like Cher to the laughter of her cast.

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Kaley Cuoco suggests Penny is a one-word name like Cher to the laughter of her cast.
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CBS

Take that with a grain of salt. The rest of the cast laughed aloud at that response.

“Big Bang Theory” star Jim Parsons pointed out that even when Penny’s father and mother joined the show, they were never referred to by their last names.

“That’s weird,” said Parsons, who played Sheldon. “I never noticed this.”

Cuoco’s response on “The Late Show With Stephen Colbert” goes against what she told fans in the past. At 2017’s San Diego Comic-Con, Cuoco said she had an idea for Penny’s maiden name.

“I have it in my head, what I think that it is. But now I’m Penny Hofstadter, so it doesn’t matter,” said Cuoco.

During an appearance on “The Talk” before the season’s start, Cuoco said there were three things she’s love to see on the show. They were have the elevator fixed (check), have Jack White on as a guest star (nope), and learn Penny’s last name.

Kaley Cuoco received one of her three wishes on the

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Kaley Cuoco received one of her three wishes on the “Big Bang Theory” finale — a fixed elevator that she got to reveal.
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Michael Yarish/CBS

It probably shouldn’t have been a big surprise that we didn’t learn Penny’s last name. The show’s producer, Steve Molaro, told Vulture in 2013 we would most likely never learn her maiden name, mostly out of superstition.

“What name could we possibly pick that would be satisfying at this point?” said Molaro. “You know, I don’t think we will [reveal it]. We’re kind of a superstitious lot here. We’ve made it this far without knowing Penny’s last name. I think we’re good not finding out.”

But hey, maybe CBS is just leaving the door open for a future potential “Big Bang Theory” spin-off. It’s something Cuoco has said she would be into if series creator Chuck Lorre wanted it. CBS entertainment president Kelly Kahl told Deadline they’re “here to listen” when and if Lorre wants to talk about any potential spin-offs.