The Big Bang Theory Wiki

Season 1 and the series began on September 24, 2007, and ended on May 19, 2008, running for seventeen episodes. Physicists Dr. Leonard Hofstadter and Dr. Sheldon Cooper get their lives shaken up when an attractive young aspiring actress from Omaha, Nebraska named Penny moves in to the apartment across the hall from theirs. Leonard begins to become hopelessly enamored of Penny, while she feels only platonic affection for him; as a result, she finds herself putting up with his closest and ever-present friends, his roommate, Sheldon Cooper, who appears obsessive-compulsive; engineering whiz Howard Wolowitz, a desperately sex-crazed mama's boy who thinks that his 1970s-style clothing and hairstyle give him an air of cool hipness; and Dr. Rajesh Koothrappali, who cannot speak to her or other woman due to his selective mutism, unless intoxicated, where he becomes a smooth talking yet highly obnoxious womanizing flirt.


Main Cast

Recurring Cast

Guest Cast


Episode (Season/Ep#) Title Original Air Date Directed By Description
101 Pilot September 24, 2007 James Burrows After an unsuccessful visit to the high-IQ sperm bank, Leonard (Johnny Galecki) and Sheldon (Jim Parsons) return home to find out Penny (Kaley Cuoco), a new neighbor, has moved in across the hall. Leonard immediately becomes interested in her.
102 The Big Bran Hypothesis October 1, 2007 Mark Cendrowski When Sheldon and Leonard go over to Penny's apartment to drop off a box of furniture that came for her, Sheldon is deeply disturbed when he sees how messy and disorganized her apartment appears. Later that night, while Penny sleeps, Sheldon sneaks into her apartment to clean and organize it; Leonard catches him and reluctantly helps him.
103 The Fuzzy Boots Corollary October 8, 2007 Mark Cendrowski When Leonard sees Penny kissing a guy in front of her apartment door, he is devastated thinking she has "rejected" him. The guys convince him to ask someone out at work, so he asks out fellow scientist Leslie Winkle, who preemptively turns him down. Leonard then asks Penny out, while Penny thinks that she is having dinner with the gang.
104 The Luminous Fish Effect October 15, 2007 Bob Koherr Sheldon is fired from his job as a physicist at the university when he insults his new boss Dr. Eric Gablehauser. His change of circumstance sends him into a downward spiral of depression which Leonard tries to cure by sending for Sheldon's mom, Mary Cooper.
105 The Hamburger Postulate October 22, 2007 Andrew D. Weyman While eating at the Cheesecake Factory where Penny works, the guys run into Leslie Winkle and she suggests that Leonard play in her string quartet as they are in need of a new cellist. Later, after the practice in Leonard and Sheldon's apartment, Leslie offers herself to Leonard and they have sex.
106 The Middle Earth Paradigm October 29, 2007 Mark Cendrowski The guys are invited to Penny's Halloween party, first turning it down as they don't dance but changing their mind when costumes are mentioned. Later, Penny's ex-boyfriend Kurt shows up.
107 The Dumpling Paradox November 5, 2007 Mark Cendrowski Penny's promiscuous friend Christy from Nebraska is in town, and ends up being seduced by Howard. The pair takes over Penny's apartment, causing her to sleep on Leonard and Sheldon's couch for the night.
108 The Grasshopper Experiment November 12, 2007 Ted Wass Rajesh's parents set him up on a blind date and he fears he won't be able to talk to her. Penny needs to practice her bar tending skills for work and once Rajesh drinks he can talk to her. On the date with Lalita he is an obnoxious drunk and she is all too happy to leave with Sheldon when he starts to flatter her.
109 The Cooper-Hofstadter Polarization March 17, 2008 Joel Murray Cleaning up after an internet experiment, Leonard discovers a letter in the trash can. He and Sheldon had been invited to present some research they had done together at a physics conference. However Sheldon does not believe in such things and says if he won't go, no one can. Leonard defies him and says he will go and present the findings on his own.
110 The Loobenfeld Decay March 24, 2008 Mark Cendrowski Leonard hears Penny singing and it is not good. When she asks him to come to a showcase he lies and says that he and Sheldon have plans. Sheldon is uncomfortable with the lie which Leonard gives and so comes up with a new one which takes on a life of its own.
111 The Pancake Batter Anomaly March 31, 2008 Mark Cendrowski When Sheldon becomes ill Leonard runs away. Howard and Rajesh join him in hiding because of how needy Sheldon becomes. Penny ends up having to look after him.
112 The Jerusalem Duality April 14, 2008 Mark Cendrowski Dennis Kim,  a child genius is looking around the university and seems to have outstripped Sheldon in every way. Sheldon decides to give up his own work and focus on other tasks. These annoy the guys so much that they try to distract Dennis.
113 The Bat Jar Conjecture April 21, 2008 Mark Cendrowski It's the annual Physics Bowl and the usual competition isn't going to be competing (they got a gig as a barbershop quartet playing Knotts Berry Farm), so the four guys form a team, but end up booting Sheldon off their team because he is being a pain. They recruit Leslie Winkle, Sheldon's nemesis.
114 The Nerdvana Annihilation April 28, 2008 Mark Cendrowski Leonard accidentally buys a full size prop of the time machine from the movie The Time Machine. As the guys attempt to bring it up to their apartment they block the stairs and Penny ends up missing work. She scolds Leonard for having all these toys and so he tries to get rid of them.
115 The Porkchop Indeterminacy May 5, 2008 Mark Cendrowski The guys see an attractive woman in Sheldon's office and can not believe their eyes. The woman turns out to be his twin sister Missy, who was in town for a wedding and needed Sheldon to sign some papers for her father's estate. The boys are smitten with her and Leonard insists she stay with them. The boys instantly try to hit on her causing her to take refuge at Penny's place.
116 The Peanut Reaction May 12, 2008 Mark Cendrowski When Penny finds out that Leonard has never had a birthday party she decides to throw him a surprise one despite Sheldon's objections.
117 The Tangerine Factor May 19, 2008 Mark Cendrowski After another messy break up Penny asks Leonard why she can't go out with a nice honest guy. So he asks her out. She says yes, but they both feel nervous about it and go to Sheldon for advice.


The first season was successful, reaching an average of 8.5 million views per episode.