Throughout its 12 seasons, The Big Bang Theory was able to welcome some major guest-stars. As expected, the guests had just as much fun as the cast did, particularly given the easy-going nature of those working on the show.

Star Wars legend Mark Hamill was among the biggest gets for Chuck Lorre, Bill Prady and Steve Holland on The Big Bang Theory. In the following, we're going to take a closer look at how the cameo came to be. As we'll reveal, Hamill didn't need much convincing and in fact, there was no concrete script in place once he accepted the offer.

We'll reveal what the actor was like behind the scenes during the filming of the show, and how his appearance was viewed by the cast and showrunners.

Mark Hamill Agreed To Appear On The Big Bang Theory Without Reading A Script

Getting a major name like Mark Hamill was a major accomplishment for The Big Bang Theory. Showrunner Steve Holland opened up about the negotiation process behind the scenes with THR. Holland notes that he was one of the first names the show thought of for the special wedding episode. Once they reached out, Hamill initially hesitated given that he didn't have a script or firm idea for what was in store.

Holland recalls, "When we started talking about the wedding episode, Mark was the first name on the list," Holland tells The Hollywood Reporter. "I'm a huge, lifelong Star Wars fan, and we started talking about fun guest-stars and were making our dream list — and Mark was at the top of it."

"We had a rough shape of what the episode was going to be, but we didn't have all the specifics," Holland says. "We got him on the phone and told him what our thoughts were. He was understandably nervous about not having to commit to something, especially committing to the role he's playing without seeing a script.

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After going in and talking to the writers behind the scenes, Hamill decided to make the commitment and agreed to appear without reading a single word.

"But he came in and talked to us for a few hours and hung out with the writers. We had a good time together, and he luckily decided to trust us and take a leap of faith. He signed on without seeing word one."

The end result was not only a positive one on-screen, but things were just as great behind the camera.

Mark Hamill Had A Blast On The Big Bang Theory And Was A Class Act Behind The Scenes With The Cast

It should not come as a surprise or shock, but Steve Holland notes that Mark Hamill was a complete class act behind the scenes on The Big Bang Theory. Not only was the actor generous with his time, but he was also open to whatever the show had in store for him.

"He was so genuinely nice and generous with his time, so happy to take selfies with people, so happy to chat with people," Holland revealed. "From a professional sense, he certainly had ideas for things that he wanted to do, but was willing to give anything we asked him to do a shot. It was just a dream come true. He couldn't have been nicer.

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Holland also praised Hamill's effortless transition into the sitcom filming genre. Making such a jump isn't always easy, but the actor was a complete natural.

"It's not always the easiest transition for film people to multicam, but he's done theater and a ton of voice work and was effortlessly good at it and really funny."

Clearly, a positive experience for Hamill and one he doesn't regret.

Billy Bob Thornton Also Agreed To A Big Bang Theory Cameo Because Of His Mom

Looking at the list of guest stars alone, it is clear The Big Bang Theory was a smash hit.

Among other major names to cameo on the series includes Billy Bob Thornton. The actor took part in the series due to a quote about his mom loving the sitcom. After the interview, Chuck Lorre took note and got in contact with his team. As they say, the rest is history.

"I said in an interview that my mom's favorite show was The Big Bang Theory. So [exec producer] Chuck Lorre got a hold of my manager and said, 'Would you consider doing a guest spot for your mom?' And I said absolutely, because I'll do anything for my mom."

Billy Bob Thornton's role was a successful one, though he did have a specific request prior to guest-starring, which included a romance storyline with Penny. The actor got his wish, but fans hoped they would've seen more of the actor down the road on the series.