Chuck Lorre initially had Johnny Galecki in mind to play the role of Sheldon. The two had worked on a movie together way back in the day — when Johnny was about 12 — and had toiled on "Roseanne" at the same time, so they knew each other fairly well. Johnny was in New York doing a play when Chuck called him up with the idea for "Big Bang" and after hearing the concept, Galecki said, I think I'm more interested in the Leonard character. He said he saw the Penny/Leonard relationship as promising and because he rarely gets to play that sort of male lead role, Leonard seemed exciting to him.
Koothrappali's original first name? Dave. Yeah. The initial concept for that character was American born to Indian parents, but when Kunal came in to audition, he — in Simon Helberg's words — "was just so Indian" that they switched it up. They also let Kunal pick his character's first name.
Carol Ann Susi is the actress who voices the role of Wolowitz's mom. Look her up, you'll definitely recognize her from one TV credit or another, and yeah, that'll be your only chance of seeing what Wolowitz's mommy looks like. "It's a spectacular voice, isn't it?" Chuck Lorre said when asked if we'll ever see the character onscreen. "I think it's best left to the imagination." Wolowitz's pop on the other hand? They're thinking Ringo Starr. No joke.
The Barenaked Ladies theme song? Almost didn't exist. The-Powers-That-Be didn't want them to do it. They said, that's just going to take time out of your episodes. But Chuck and Bill insisted and are so glad they did, because the result is, well, you know, it's pretty great. "They nailed it," Chuck said, referring to the Barenaked Ladies who they approached to compose the song. Their guidelines: Cover everything in the history of the world in 15 seconds.
This cast hates each other. They don't get along at all.
No, quite the opposite, they actually hang out all the time — I've seen them on the town together a lot actually — and the dynamic they've got going is eerily similar to their characters. Actually, it's kind of awesome. They tease and heckle each other as real friends do and, yes, we should all be jealous, they're living the TV dream, old school sitcom style…