The Big Bang Theory Episodes

Brain doesn't have much of a chance against brawn when Leonard and Sheldon try to retrieve Penny's TV from her muscle-bound ex.

Leonard tries to keep Sheldon from fighting chaos in the universe, the center of which is Penny's messy apartment.

Leonard has a date - with Penny. Too bad he hasn't told her about it.

Fish night lights. Hand-loomed ponchos. A visit from Mom. Things get freaky when Sheldon gets fired.

Leonard's relationship with co-worker Leslie takes an unexpected turn, causing Sheldon to ponder the meaning of a tie on a doorknob.

Leonard discovers "hobbit" is the wrong costume to wear to Penny's Halloween party when her ex-boyfriend shows up. Also, Sheldon is not a zebra.

Wolowitz gets a girl. Penny beats Sheldon at Halo. Sometimes truth is stranger than science fiction.

Rajesh flips over his gorgeous blind date. But she only has eyes for Sheldon. Sheldon?!

Leonard and Sheldon go from physics to fisticuffs when tempers flare at the symposium.

Sheldon cannot tell a lie. He has to tell at least seven. And they are all "un-unravelable!"

Everyone knows to head to the hills when Sheldon gets sick. Everyone except Penny, that is.

When a child prodigy arrives on campus, Sheldon graciously sets out to destroy him.

Sheldon is the MVP on the guys' Physics Bowl team: "Most Vain Physicist."

Leonard is thrilled with his prop time machine from the 1960 film, until Penny tells him it's unhip to play Morlocks and Elois.

Sheldon's twin Missy is nothing like Sheldon...which makes her the other guys' newest dream girl.

Leonard's birthday finds Wolowitz and Leonard in the ER and Penny and Sheldon sharing a shopping trip from hell.

Nervous about their first date, Leonard and Penny seek advice from the same romance-savvy sage: Sheldon.

Can you keep a secret? Sheldon can't, as Penny discovers when she confides in him about her date with Leonard.

After his romance with Penny goes toes up, Leonard rebounds into the arms of Sheldon's nemesis, Leslie Winkler.

Sheldon gets Penny playing Age of Conan online. Before you can say "quest to the black castle", she's hooked.

When People names Raj one of the "30 Under 30 to Watch", watch out. The honor goes straight to his head.

The guys talk Sheldon into finally learning how to drive. What could possibly go wrong?

Tall, dark and handsome. One out of three is enough for a pretty grad student with designs on Sheldon.

This means war. Hostilities escalate after Penny violates some of Sheldon's weird house rules.

To impress a girl, Howard takes her to the Mars Rover control room - and promptly drives the Rover into a Martian ditch.

"Now we've got McCoy!" Star Trek enthusiast Sheldon is thrilled that Leonard is dating a doctor.

When Stephanie puts her relationship with Leonard into romantic overdrive, Leonard turns to Penny for advice.

Penny gives Sheldon the most exciting, wonderful, amazing Christmas present ever. Sheldon gives Penny soap.

Penny's cutting remark crushes Howard's spirit just before the guys' big fighting-robot competition.

Let others use charm, kindness or congeniality to make friends. Sheldon would rather employ science.

Penny's financial problems stem from a loan that Kurt, her loser ex-boyfriend never repaid.

Leonard's analytical, self-absorbed, socially tone-deaf mother visits. Sheldon immediately bonds with her.

Howard Wolowitz, boy toy. Leslie treats Howard like a sex object when the unlikely duo hits the sheets.

Traveling to San Francisco on the Coast Starlight, the guys meet a star: Summer Glau of "Terminator: The Sarah Connor Chronicles."

Capitalism is an eye-opening experience when Sheldon combines web commerce with his very first cup of coffee.

Penny is no longer the belle of the building when another hot blonde moves in - and moves in on the guys.

Heartbroken that Penny's dating the ultimate nerd - a comic salesman - Leonard tries the bar scene with Howard and Raj.

Vegas, baby! In Sin City, the guys hire a Jewish hooker to snap Howard out of his dumped-by-Leslie funk.

That flushing sound you hear is Howard's career. His International Space Station toilet design is a washout.

When the guys arrive in the Arctic for a summer-long scientific expedition, they discover the place to be strangely familiar.

Sheldon flees back to Texas in disgrace when he learns the guys tampered with his arctic expedition data, forcing the guys to follow him and threatening Leonard's hopes for a romantic encounter with Penny.

Leonard and Penny struggle to recover from an awkward first hookup while Sheldon and Howard stake their best comic books on a bet to determine the species of a cricket.

Howard and Raj visit a Goth nightclub to pick up women while Sheldon attempts to build a better Penny using chocolate-based behavior modification.

Raj must find a new job or be sent back to India, but Sheldon has a solution, which leaves Leonard and Penny dealing with Howard as third wheel.

While Sheldon settles a score with his nemesis, Wil Wheaton, Wolowitz begs Leonard to get Penny to set him up with one of her friends.

Sheldon teaches Leonard how to understand football while a kite-fighting incident threatens Howard and Raj's friendship.

An argument between Leonard and Penny proves "inconvenient" to Sheldon.

With Leonard, Howard and Raj away camping in the desert, an injured Penny has only Sheldon to rely on.

After he's humiliated on National Public Radio, Sheldon vows to destroy Kripke, while Wolowitz tries not to destroy his new relationship with Bernadette.

Sheldon attempts to help Penny understand Leonard's work, and Wolowitz becomes jealous when Leonard starts hanging out with his new girlfriend.

A visit from Leonard's mother delights Sheldon and horrifies Leonard.

While Sheldon and Koothrappali attend a university mixer, Leonard is upset to discover that Penny believes in psychics.

When their apartment is robbed, Leonard and Sheldon turn to their friends to create a state-of-the-art security system.

Sheldon's search for the answer to a physics problem leads him to work at the Cheesecake Factory with Penny.

Leonard can only bring one guest on a trip to see CERN's Large Hadron Collider (the world's largest and highest energy particle accelerator) in Switzerland on Valentine's Day.

Sheldon winds up in traffic court when he gets a ticket because of Penny.

When the guys find a ring from "The Lord of the Rings" at a garage sale, it threatens to tear them apart.

Sheldon's friends come to his aid when his fear of public speaking stands between him and a coveted award.

A fight between Leonard and Penny threatens their relationship, while Sheldon battles Wil Wheaton in bowling.

When Leonard and Penny aren't speaking, Sheldon goes to extremes to keep them both happy.

Leonard and Sheldon compete for the attention of a famous female physicist.

Leonard tells Penny about how he met Sheldon for the first time ... and what happened to the elevator.

While Penny worries that dating Leonard has ruined her for normal guys, Wolowitz and Koothrappali search for Sheldon's perfect match online.

Howard uses a robotic arm for his own pleasure. Penny assists Sheldon with his first date.

Sheldon realizes that by the time he downloads his consciousness into a robot body, he'll be dead, so he tries to make himself live longer.

When Sheldon "breaks up" with Amy, the guys worry as he tries to find a companion to replace her.

Wolowitz tries to get back together with Bernadette. Sheldon and Raj go to war at the university.

Leonard is depressed to realize all the other guys have girlfriends, while he doesn't. Amy wants to introduce Sheldon to her mother.

A visit from Raj's sister coincides with Leonard becoming secretive.

The rest of the gang is interviewed by the FBI for Wolowitz's security clearance.

The guys camp out in line to see a movie, but have their plans jeopardized by Wil Wheaton. Penny and Bernadette invite Amy over for a slumber party.

Penny asks Leonard to lie to her father, while Howard, Raj and Bernadette pull an all-nighter at a telescope.

Amy crushes on one of Penny's dim ex-boyfriends, Zack. Raj and Wolowitz argue over who'd be the better superhero.

The guys rope Zack into their costume contest entry as the Justice League

Their friendship becomes strained when Sheldon tries to take over Leonard's creation of a smartphone application that solves differential equations.

A science convention at a hotel leads to Bernadette running into an ex-boyfriend and Wolowitz worrying he can't quite compare.

To improve his skills as an instructor, Sheldon asks Penny to give him acting lessons.

After meeting at a fundraising gala, an aged, but wealthy, Caltech donor makes Leonard ponder if he is willing to have sex with her to secure a donation.

Bernadette tells Howard that it is time to choose between her or his mother. Leonard discovers that Priya is back in town and Amy tries to comfort Penny.

Realizing Leonard is the center of the gang, Sheldon seeks a new group of friends where he can be the center.