Kripke is back, and the lisping "super villain" wants to knock Sheldon off his perch as the top dog at work when the rivals face off on Thursday's The Big Bang Theory.

After learning that the corner office at the university is up for grabs at work, Kripke (John Ross Bowie) and Sheldon (Jim Parsons) — two most unlikely athletes — will battle it out as they compete in a series of sports challenges, with the winner nabbing the spacious prize.

Howard will get some real space cred on Thursday's episode of The Big Bang Theory.

NASA astronaut Mike Massimino guest stars as himself in the installment that features Simon Helberg's alter ego inch closer to his spring launch to the International Space Station as a payload specialist.

In the episode, Howard will not-so-modestly show off a press release that notes his participation in the voyage -- and his quest to earn a nickname from his fellow astronauts, including Massimino.

Leonard and Penny 2.0 officially kick off Thursday when CBS' The Big Bang Theory picks up on the heels of its risky 100th episode that saw the pair reunite -- but is the couple made for each other?

After envisioning -- and over-thinking -- what could happen should he ask her on a date and, despite the horrible outcomes, Leonard (Johnny Galecki) took the big step anyway at the end of the 100th episode and went for it.

[Warning: This story contains spoilers from Thursday's "The Recombination Hypothesis" episode of The Big Bang Theory.]

The concept for Thursday's 100th episode of The Big Bang Theory -- in which Leonard (Johnny Galecki) and Penny (Kaley Cuoco) reunite -- started well before Thanksgiving with an email from Chuck Lorre to Bill Prady and Steve Molaro.

For a show about the lives of science geeks and the people who love them, CBS’ The Big Bang Theory has had its fair share of nerd moments.

When CBS’ The Big Bang Theory airs its 100th episode Jan. 19, it will be a look at what has come before for the show’s pivotal couple, Penny and Leonard, as well as the on-again/off-again duo’s future in a unique way.

“We went back and watched the pilot, and we talked about that, and we tried to do a 100th episode that connects emotionally to the pilot,” co-creator/EP Bill Prady tells The Hollywood Reporter during a December event celebrating the milestone at the California Science Center in Los Angeles.

The Big Bang Theory’s recent female infusion comes to a head Thursday when Amy goes on a date with Stuart, forcing Sheldon to explore what jealousy is and what it means when it comes to the nature of his relationship with his female counterpart.

For the show, however, the recent wave of girl time can be viewed in multiple ways, according to co-stars Mayim Bialik and Melissa Rauch, who play Amy Farrah Fowler and Bernadette Rostenkowski, respectively, on the CBS ratings winner.