The Best Episodes of The Big Bang Theory

What happens when hyperintelligent roommates Sheldon and Leonard meet Penny, a free-spirited beauty moving in next door, and realize they know next to nothing about life outside of the lab. Rounding out the crew are the smarmy Wolowitz, who thinks he's as sexy as he is brainy, and Koothrappali, who suffers from an inability to speak in the presence of a woman.

The Bath Item Gift Hypothesis

#1 - The Bath Item Gift Hypothesis

Season 2 - Episode 11

Penny starts dating Leonard's handsome colleague; Leonard and his friends are tortured by Sheldon's obsession with gift-giving etiquette.

star 8.40
2,740 votes
The Thanksgiving Decoupling

#2 - The Thanksgiving Decoupling

Season 7 - Episode 9

An upset Sheldon protests when the entire gang drags him to Mrs. Wolowitz's house for Thanksgiving. Meanwhile, Penny and Leonard must deal with a mistake from her past.

star 8.35
4,457 votes
The Roommate Transmogrification

#3 - The Roommate Transmogrification

Season 4 - Episode 24

When Bernadette receives her PhD, Wolowitz feels emasculated. Raj and Leonard swap places and Penny does something she's regrets.

star 8.30
2,573 votes
The Countdown Reflection

#4 - The Countdown Reflection

Season 5 - Episode 24

The fifth season ends with Howard and Bernadette deciding to get married before his NASA mission, causing the gang to scurry into overdrive in an effort to stage the wedding. NASA astronaut Mike Massimino has a cameo as himself.

star 8.29
2,698 votes
The Good Guy Fluctuation

#5 - The Good Guy Fluctuation

Season 5 - Episode 7

A cute comic book artist puts Leonard and Priya’s relationship to the test, while Sheldon tries to scare the guys for Halloween.

star 8.29
2,936 votes
The Scavenger Vortex

#6 - The Scavenger Vortex

Season 7 - Episode 3

When the entire gang competes in a cutthroat scavenger hunt designed by Raj that tests their science knowledge and street smarts, it brings out the best – and worst – in everyone.

star 8.27
4,530 votes
The Romance Resonance

#7 - The Romance Resonance

Season 7 - Episode 6

Sheldon's latest scientific breakthrough makes him feel like a fraud – and threatens to haunt him forever. Meanwhile, Howard's romantic gesture to Bernadette causes Penny to step up her game with Leonard.

star 8.25
4,491 votes
The Closure Alternative

#8 - The Closure Alternative

Season 6 - Episode 21

Amy tries to help Sheldon get over his compulsive need for closure when one of his favorite TV shows is canceled; Raj discovers a secret about Lucy.

star 8.25
3,606 votes
The Hawking Excitation

#9 - The Hawking Excitation

Season 5 - Episode 21

When Wolowitz gets to work with Stephen Hawking, Sheldon is willing to do anything to meet his hero.

star 8.23
2,689 votes
The Love Spell Potential

#10 - The Love Spell Potential

Season 6 - Episode 23

Amy and Sheldon's relationship takes a surprising turn during a game of "Dungeons & Dragons"; Lucy and Koothrappali have an awkward date.

star 8.23
3,607 votes
Directors: Anthony Rich
The Lunar Excitation

#11 - The Lunar Excitation

Season 3 - Episode 23

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

star 8.23
2,487 votes
Directors: Peter Chakos
The Beta Test Initiation

#12 - The Beta Test Initiation

Season 5 - Episode 14

Leonard and Penny deal with the idea of starting a relationship again and Raj finally finds a "woman" he can talk to without being drunk, in the form of Siri on his new phone. Meanwhile, Sheldon decides to start a YouTube series entitled "Sheldon Cooper presents Fun with Flags" with the help of Amy.

star 8.22
2,664 votes
The Long Distance Dissonance

#13 - The Long Distance Dissonance

Season 10 - Episode 24

The gang is concerned when Sheldon’s former admirer, Dr. Ramona Nowitzki, resurfaces while Amy is away at Princeton.

star 8.21
8,018 votes
The Tenure Turbulence

#14 - The Tenure Turbulence

Season 6 - Episode 20

The girls get involved when Leonard, Sheldon and Raj compete for tenure at the University.

star 8.19
3,535 votes
The Werewolf Transformation

#15 - The Werewolf Transformation

Season 5 - Episode 18

Sheldon becomes agitated when his regular barber is out sick. Astronaut training causes Howard to reconsider wanting to go into space. Penny beats Leonard in chess, the first time she plays.

star 8.19
2,608 votes
The Fish Guts Displacement

#16 - The Fish Guts Displacement

Season 6 - Episode 10

When Amy gets sick, Sheldon tries to nurse her back to health; Wolowitz and his father-in-law plan a fishing trip.

star 8.19
3,060 votes
The Launch Acceleration

#17 - The Launch Acceleration

Season 5 - Episode 23

When NASA moves up Howard's mission, he must face his fears and Bernadette's dad, thus putting the wedding plans in jeopardy. Meanwhile, Leonard says something surprising to Penny in the bedroom.

star 8.19
2,645 votes
The Opening Night Excitation

#18 - The Opening Night Excitation

Season 9 - Episode 11

As the guys prepare to go to the premiere of the new Star Wars movie, Sheldon plans a special event for Amy's birthday.

star 8.19
6,204 votes
The Indecision Amalgamation

#19 - The Indecision Amalgamation

Season 7 - Episode 19

Raj struggles with guilt when he dates two women at once; Penny has a chance to play a part in a cheesy movie; Sheldon is torn between two gaming systems.

star 8.19
4,358 votes
The Prestidigitation Approximation

#20 - The Prestidigitation Approximation

Season 4 - Episode 18

Sheldon is baffled by Wolowitz's magic trick. Meanwhile, Leonard realizes dating Priya may make it impossible to continue being friends with Penny.

star 8.19
2,590 votes
The Herb Garden Germination

#21 - The Herb Garden Germination

Season 4 - Episode 20

Sheldon and Amy decide to start several rumors about the others as a test. Meanwhile, Howard takes his relationship with Bernadette to even higher level.

star 8.18
2,536 votes
The Egg Salad Equivalency

#22 - The Egg Salad Equivalency

Season 6 - Episode 12

When Sheldon is accused of sexual harassment, he ends up getting Raj, Leonard and Wolowitz in trouble.

star 8.17
3,060 votes
The Tangerine Factor

#23 - The Tangerine Factor

Season 1 - Episode 17

Penny's break-up spurs Leonard to summon the courage to ask her out, and each goes to Sheldon for advice on their upcoming date.

star 8.17
2,545 votes
The Bakersfield Expedition

#24 - The Bakersfield Expedition

Season 6 - Episode 13

As the guys don costumes and go on a road trip to a comic book convention, the ladies decide to stay home and try to interpret a comic book.

star 8.17
2,914 votes
The Staircase Implementation

#25 - The Staircase Implementation

Season 3 - Episode 22

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

star 8.17
2,586 votes