One of The Big Bang Theory's biggest mysteries will remain just that forever.
The maiden name of Penny (played by Kaley Cuoco) has never been revealed and that's the way it's going to stay, according to the show's producer.
"(Eventually) we got nervous and superstitious about giving her one," Molaro said at WonderCon.
Penny married Leonard Hofstadter (played by Johnny Galecki) at the start of season 9 and Molaro said about the character's surname, "it will always be Hofstadter".
The 12th and final season of The Big Bang Theory is currently airing in the US and the last episode ever will screen in May.
The show's writers told the WonderCon crowd that saying farewell to the characters they created and have been so close to for years has been a hard process, but they got some friendly advice from Friends creator Marta Kauffman.
"A few of us were at an event and saw (her)," writer Tara Hernandez said, as reported by The Hollywood Reporter.
Kauffman's advice to them was: "It's going to be so hard on you. But you'll fall in love with the next one. You have to fall in love with the next (show)."
Here are some fun facts you might not know about The Big Bang Theory.
KALEY CUOCO WASN'T IN THE PILOT
Kaley Cuoco wasn't originally cast as the female lead in The Big Bang Theory.
She auditioned twice but missed out on the role to fellow actor Amanda Walsh.
However, after CBS gave the pilot episode the thumbs down, creator Chuck Lorre decided to mix things up and invited Cuoco to come back and test for the part again.
"Third time's the charm!" joked Cuoco to Vegas magazine about landing the role.
THE PILOT HAD A COMPLETELY DIFFERENT THEME SONG
The Barenaked Ladies' Big Bang theme song is iconic now, but it wasn't even the original choice for the show.
For the pilot episode, Thomas Doly's 1980s tune She Blinded Me With science was used instead — but clearly it didn't stick, and was soon replaced with the current song.
KALEY CUOCO AND JOHNNY GALECKI DATED FOR YEARS
Kaley Cuoco is close to all of her Big Bang co-stars, but she's especially close to Johnny Galecki who plays Leonard on the show.
"We dated for almost two years," she revealed to Watch! magazine in 2010.
"It was such a huge part of my life and no one knew about it. It was a wonderful relationship but we never spoke a word about it and never went anywhere together.
"I'm so lucky it was a mutual ending and that we don't hate each other. We've seen that happen on other shows."
SHELDON'S SHIRTS OFTEN REPRESENT HIS MOOD
Green Lantern fans are probably already aware of this, but for the rest of us: Sheldon is often wearing different-coloured shirts bearing the Lantern's logo but each shirt has a different emotion attached to it in the comic world.
For example — red is rage, blue is hope and indigo is passion.
A lot of the time, Sheldon's behaviour in a particular scene is mirrored by the colour of his shirt.