The Big Bang Theory: The Complete First Season
University physicists Leonard and Sheldon know whether to use an integral or a differential to solve the area under a curve. But they don’t have a clue about girls. Or dating. Or clothes. Or parties. Or having fun. Or, basically, life. So when a pretty blonde named Penny moves in the apartment across the hall, the guys decide to get an education outside of the classroom. Boys, you have a lot to learn. With series creators Chuck Lorre (Two and a Half Men) and Bill Prady (The Gilmore Girls) concocting the right mix of logic and lunacy and stars Johnny Galecki (Roseanne) and Jim Parsons (Judging Amy) turning geekdom into Phi Beta fun, The Big Bang Theory is big on laughs. And life.

The Big Bang Theory: The Complete Second Season
The science of funny is back! At work, physicists Leonard and Sheldon and their geek pals conquer the cosmos. At home, real life from dating to driving conquers them. This season, Leonard gets a girl. So does Sheldon. (Sheldon?!) Howard drives the Mars Rover into a ditch. Raj woos a terminator. Gorgeous girl-next-door Penny falls under the spell of Age of Conan. And super-smart, überconfident Leslie Winkle reduces mere men to spineless jellyfish. Twenty-three laugh-filled episodes from series creators Chuck Lorre (Two and a Half Men) and Bill Prady (Dharma & Greg) and a talented cast with astronomical comedy I.Q.s show why Big Bang is such a big hit.

The Big Bang Theory: The Complete Third Season
From Emmy® nominees Chuck Lorre (Two and a Half Men, Dharma & Greg, Cybill, Grace Under Fire) & Bill Prady (Dharma & Greg) comes The Big Bang Theory. Leonard (Galecki) and Sheldon (Parsons) are brilliant physicists, the kind of "beautiful minds" that understand how the universe works. But none of that genius helps them interact with people – especially women. All this changes when a free-spirited beauty named Penny (Cuoco) moves in next door. Sheldon, Leonard's roommate, is quite content spending his nights playing Klingon Boggle with their socially dysfunctional friends, fellow Caltech scientists Howard Wolowitz (Helberg) and Rajesh Koothrappali (Nayyar). Leonard, however, sees in Penny a whole new universe of possibilities ... including love.

The Big Bang Theory: The Complete Fourth Season
“Four seasons in, it is still laugh-out-loud funny. Every episode, every week,” USA Today’s Robert Bianco says about the hit series The Big Bang Theory. Here’s your chance to subject his conclusion to empirical analysis by watching all 24 Season 4 Episodes! This season the Big Bang gang’s romantic universe expands. On the rebound from Penny, Leonard falls into the arms of Raj’s sister Priya. Sheldon gets a girlfriend, or rather a friend who is a girl: Amy, a dour neurobiologist who declares herself besties with Penny. Howard and Bernadette heat up. And so do Raj and Bernadette (at least in Raj’s Bollywood daydream). All in the furtherance of award-winning genius comedy.

The Big Bang Theory: The Complete First Season
The delightful sitcom The Big Bang Theory revolves around a character type rarely seen on television: The alpha geek. Physicists Leonard (Johnny Galecki) and Sheldon (Jim Parsons) get their lives shaken up when an attractive young woman named Penny (Kaley Cuoco) moves in to the apartment across from theirs. The key to the show, though, is not that they both fall haplessly in love--Leonard does, but Sheldon remains impermeably aloof and caustic about anything resembling romance or human relationships in general. While the push and pull of Leonard's yearning for Penny motivates much of the series' ongoing plot, the show's real drive comes from Sheldon's fantastic combination of obsessive-compulsive neurosis and grandiose obliviousness. He's a brilliant comic creation, imperious and dorky, a seamless collaboration of clever writing and an inspired performance by Parsons. Whether Sheldon loses his job for insulting his new boss, or finds his ego bruised by a child prodigy, or finds himself unable to bear being part of a lie that Leonard has told, he attacks the world with a relentless need to assert his supremacy--and the results are deeply funny.

The triumph of The Big Bang Theory is that everyone is written with genuine affection; what could have been a lifeless parade of stereotypes--Two Nerds and a Hot Chick--becomes instead a charming collision of cultures. The familiar stuff (computer games, comic books, social incompetence) has the grit of specificity; the show understands the difference between Halo and Halo 3, knows what the Bottle City of Kandor is, and grasps the infinite variety of ways in which a conversation can go terribly awry. (Penny gets less nuance, but Cuoco still gives her a distinctive personality.) Kudos as well to supporting players Simon Helberg and Kunal Nayyar, who bring their own variations on geekiness to the table, and to great appearances by some of Galecki's former cohorts on Roseanne--Sara Gilbert as geekette Leslie and Laurie Metcalf as Sheldon's fundamentalist mother. All in all, one of the most winning sitcoms in years. --Bret Fetzer

The Big Bang Theory: The Complete Second Season
Early in the second season of The Big Bang Theory, Sheldon (Emmy nominee Jim Parsons) asks Penny (Kaley Cuoco), "When did we become friends?" For a smart guy, Sheldon misses a lot. But for the record, season 1 answered the question of whether or not an adorkable group of geniuses can become friends with the hot girl next door (yes!). Season 2 shows us what that friendship looks like, and it's awesome, especially when it includes a rousing game of "Rock, Paper, Scissors, Lizard, Spock." Sheldon's roommate Leonard (Johnny Galecki) wants to be more than friends with Penny, but the richest relationship of the show is that of Penny and Sheldon. He uses the "covenant of friendship" to get Penny to give him rides, he engages in an over-caffeinated business venture with her, and in the excellent Christmas episode, they exchange gifts and share a surprisingly touching moment. (Sheldon's midseason efforts to befriend a colleague can't compare.) Penny is forever changed by the guys, even telling a date about Schrodinger's cat and delving into online gaming. The extras, including a gag reel and interviews with the cast and crew, reveal the stars to be as appealing and connected to each other as their characters. --Stephanie Reid-Simons

The Big Bang Theory: The Complete Third Season
The third season of the wonderfully smart and silly comedy The Big Bang Theory is even better than the first two. When Sheldon, Leonard, Howard, and Raj--the show's quartet of supreme geeks--return from their research expedition in the Arctic, Leonard and his adorable neighbor Penny fall into each other's arms. In most TV shows, losing that sexual tension would deflate the entire series, but the writers and performers of The Big Bang Theory navigate these treacherous waters with aplomb; after a weak couple of episodes, the show regains its bearings with faux tattoos, sneaky behavior modification, lessons in football, a dislocated shoulder, a trip to Switzerland, pot brownies, and the one true Ring. Guest appearances by comic book legend Stan Lee, Katee Sackhoff from Battlestar Galactica, and former Star Trek boy genius Will Wheaton as themselves are used to remarkably good effect, and Simon Helberg and Kunal Nayyar, as Howard and Raj, get better story lines than ever before.

But make no mistake: Jim Parsons, as Sheldon, drives the show. With Leonard (Johnny Galecki) and Penny (Kaley Cuoco) grappling with fairly conventional relationship issues, it falls to Sheldon to turn every potential cliché into an opportunity for unexpected lunacy. His combination of ruthless rationality, profound narcissism, and yawning neediness make Sheldon a remarkable comic creation, and Parsons plays him to the hilt. Even funnier than his relentless analytical approach to emotions is when he tries to be more human; his attempts to comfort Penny when she's injured are hilariously unnerving. Watching Sheldon "grow" over the course of The Big Bang Theory's progress is one of the show's greatest pleasures. --Bret Fetzer

The Big Bang Theory: The Complete Fourth Season
The superb sitcom The Big Bang Theory launches into its fourth season with an expanded cast and a whole new set of social dynamics to go with it. It's a little unsteady at first: Sheldon (the ever-inspired Jim Parsons) denies having a girlfriend in the similarly intellectual Amy Farrah Fowler (Mayim Bialik, a long way away from Blossom), which leads to several Sheldon-dominated episodes--and as marvelous a character as Sheldon is, he can be too much of a good thing. Fortunately, things soon take a clever turn: Penny (Kaley Cuoco), Howard's girlfriend Bernadette (Melissa Rauch), and Amy become, ever so awkwardly, friends, providing an ingenious counterpoint to the socially hapless quartet of Sheldon, Leonard (Johnny Galecki), Howard (Simon Helberg), and Raj (Kunal Nayyar). Amy's emotional disconnection but fervent curiosity provides a delicious variation on Sheldon (without in any way replacing him) that gooses the show up to a new level. But episodes without her are still enjoyable--this is one of the best-written and -acted comedies on television. Though there is an odd increase in bodily function humor (perhaps the writers are trying to counter the jokes about comic books and theoretical physics), inventive stories abound: Sheldon becoming obsessed with cats; Amy's complete bafflement at becoming aroused by one of Penny's ex-boyfriends; grappling with Wil Wheaton over 21 extra seconds of Raiders of the Lost Ark; the plundering of Sheldon's World of Warcraft account; Leonard getting involved with Raj's sister Priya (Aarti Mann), much to Raj's discomfort; and much, much more. The balance of the ensemble grows increasingly skillful over the episode, giving everyone a chance to shine. --Bret Fetzer