'The Big Bang Theory' Spoilers: Billy Bob Thornton And 'Mars Attacks!' [Photos]

The Big Bang Theory is about to leave its Monday blues behind as it moves back to Thursday nights, and Billy Bob Thornton might help the series recover from its season 8 slump.

The Monday episodes of the CBS series have received some rather lukewarm reviews. Vulture writer Kimberly Potts complained that season 8 of The Big Bang Theory has featured way too many "retread sitcom plots," and Entertainment Weekly writer Dalene Rovenstine wrote that the series "wouldn't know a mature relationship if it was locked in a steam tunnel with it." This was a reference to the annoying bickering between Penny and Leonard and Howard and Bernadette in last week's "The Expedition Approximation."

Fans of The Big Bang Theory who agree that the show has grown a bit stale might not want to tune out just yet -- it could come back with a big bang when it moves back to Thursday nights on October 30. Producer Bill Prady has been teasing that the next episode is going to be a good one.

According to Star Watch Byline, the October 30 episode of The Big Bang Theory will be titled "The Interpretation Agitation." The super-secret subject that Bill Prady wasn't allowed to talk about is likely Billy Bob Thornton's guest-starring role on the episode. Major spoilers about Billy Bob's character lie ahead, so quit reading now if you want to be surprised.

The Fargo star will be playing an amorous doctor who falls in love with Penny after the pharmaceutical sales rep visits his office to peddle her products. Penny has already made it known that she flirts with doctors to sell her wares, and now it looks like this method of making sales is majorly going to backfire. Billy Bob Thornton's character tracks down Penny and shows up at her apartment to profess his love, which slightly irks Leonard. The love-starved doctor eventually ends up running into Amy, and he also falls head-over-heels for her.

This plot could lead to another fight between Penny and Leonard, and it could also cause a cute Shamy moment if Sheldon actually gets jealous of another man being affectionate towards his ladylove.

The stars of The Big Bang Theory have been sharing mysterious social media photos of themselves posing with cool movie memorabilia on the set of "The Interpretation Agitation," which you can see below.

Jim Parsons Mars Attacks Alien

"Work buddies."
Jim Parsons Gort
"Today's on-set friend. #mybodyguard"
Kaley Cuoco Mars Attacks Alien
"@themelissarauch and I having a moment with our guest star. We like to make all guests feel welcome. Even aliens."
Mayim Bialik Magneto
"Me, @themelissarauch, and Magento's helmet. Just another day at the office, Big Bang style."
The Big Bang Theory Fansite has an explanation for why the actors are hanging out with one of the aliens from Mars Attacks!, Gort from The Day the Earth Stood Still and Magneto's helmet from the X-Men movies. Sheldon ends up befriending Thornton's character, and it turns out that the doctor is a urologist who has tons of celebrity clients. Because of this, he has amassed a huge collection of movie memorabilia. He also owns one of James Cameron's kidney stones.

Billy Bob Thornton might seem like an odd guest star for The Big Bang Theory, but the actor is actually a fan of the CBS series. According to Variety, Thornton once said that he'd love to play "a guy who steals Penny away" on the show. His doctor character might not get the girl, but it should be fun to watch him try.

Are you looking forward to seeing Billy Bob Thornton on The Big Bang Theory?

[Image credits: CBS, FX, and Jim Parsons, Kaley Cuoco, Mayim Bialik via Instagram]