Along the way, The Big Bang Theory was able to bring in so many A-list type guest stars. As we'll reveal in the following, some of them wanted to add their own creative input. Billie Bob Thornton made a request of his own while on the show, wanting to work alongside a certain main character.

We're also going to take a closer look at the late Adam West and his cameo on the series. It was a special appearance for West, who appeared on episode 200 of the series. We'll take a look back at how he felt about the role, while also taking a closer look at a certain line he wanted to change. According to co-creator Bill Prady, the line was kept the same, and West had no objections.

Adam West Wasn't The Only Guest Star To Have A Specific Request During His Appearance On The Big Bang Theory

Throughout its 12 season run, The Big Bang Theory had some epic guest stars. Among the memorable list includes Stephen Hawking, Stan Lee, Bob Newhart, James Earl Jones, Bill Nye, Mark Hamill, Elon Musk, George Takei and so many others.

Among that list of stars also includes none other than, Billy Bob Thornton. His cameo was an unlikely one, after the actor revealed in an interview that his mom had love for the show.

This caused reps from the sitcom to reach out, and both sides would agree to terms.

Turns out, according to showrunner Steve Holland, the actor had a request for his appearance, and it involved a romantic storyline alongside Penny. He ended up getting his wish, at least somewhat.

"It did come up a little bit, but he basically got to try to," Molaro revealed about the actor's request.

Molaro expands, "The idea that came up of Penny taking her engagement ring off while she's working had been floating around for a while. We thought, what if Billy is this socially awkward, sympathetic doctor who doesn't quite know how to process Penny's flirtations with him.

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"We had that basic idea and went to Billy and his people ran it by them. Billy was on the phone, and he thought it was a really fun idea and was into it. That's how it began."

Fans can all agree, it all came together, and turned out to be a memorable cameo.

Adam West Wanted To Change The Line Of What Kind Of Dogs He Had, But Realized It Should Be Kept The Same

Co-creator Bill Prady retold a great story of his experience alongside Adam West during his table read on The Big Bang Theory.

According to Prady, the late actor had a minor concern that involved what kind of dogs he had.

Prady reveals with Cinema Blend, "So he was on our 200th episode and after our table read, he called me over. He had some questions about the script and he had a line in the script where he told Leonard and Koothrappali, 'Don't ring my doorbell or my poodles will go crazy.' Adam said to me, 'Do you think I could have a tougher dog, like a Rottweiler?"

Prady let West know that the scene would be funnier as is, and hilariously, not only did West agree, but he also added that he actually had poodles of his own.

"And I said, 'Well, Mr. West, you could, but I don't think it's as funny.' And he said, 'Well, I have poodles in real life, so I guess it's fine."

A minor hiccup, but great to see how open West was to giving the audience a laugh - even if it meant that he had to poke fun at himself.

Adam West Had A Blast Appearing On The Big Bang Theory

The late actor didn't appear on just any Big Bang Theory episode. He took on a memorable one which involved a milestone for the show, episode number 200.

For West, the experience was a positive one, while it helped to keep him young with a set of young actors.

"It's fun for me because I enjoy staying fresh and seeing what's in the heads and the talent of younger people. And it makes me a little cooler. But the main thing is to be able to do a very popular show with the kind of comedy that I enjoy," West reveals alongside Variety.

West added that he always fit in easily when it came to comedy, especially playing himself in a particular role.

"The rhythms for this sitcom and others I've noticed are very formulized. It works for them. And the people who have been doing it for a number of years on the show have a great advantage, of course, to some bloke who just walked in."

He continues with Variety, "But I've been able to pick up the rhythms and really adapt them to my kind of speech pattern with what they want me to play. Because I'm playing myself, which is the most difficult of all the roles."

Fans can agree, he was a natural fit during his cameo on the show.