Penny (The Big Bang Theory)
|This article relies on references to primary sources. (November 2013)|
|The Big Bang Theory character|
Kaley Cuoco as Penny
|Created by||Chuck Lorre
|Portrayed by||Kaley Cuoco|
|Nickname(s)||"Bestie" (by Amy)
"Slugger" (by Wyatt)
|Significant other(s)||Dr. Leonard Hofstadter, PhD (boyfriend/fiancé)
Zack (married before annulment in 2013)
Penny is a fictional character on the CBS sitcom, The Big Bang Theory, portrayed by actress Kaley Cuoco. Cuoco began being credited as Kaley Cuoco-Sweeting, starting with the season seven episode, "The Convention Conundrum".
Penny is the primary female character on the show, befriending her across-the-hall neighbors Leonard Hofstadter (Johnny Galecki) and Sheldon Cooper (Jim Parsons), two physicists who work at the nearby California Institute of Technology (Caltech). Penny's lack of advanced education, but outgoing personality and common sense drastically contrast with the personalities of the primary male characters in the series, even though she is considered part of their group. She is the love interest of Leonard, whom she dates regularly during the third, fifth, sixth, and seventh seasons. In the seventh season, Penny becomes engaged to Leonard.
Originally from a small town outside of Omaha, Nebraska, Penny has aspirations of becoming an actress. Until the seventh season, she worked as a waitress at the local Cheesecake Factory. She is a Sagittarius, born on December 2. She has full confidence in horoscopes and psychics, which has led to arguments with Sheldon and Leonard about their accuracy.
In contrast to the rest of the group, Penny is not well-educated or savvy in a specific technical field, but she has great social skills and is more streetwise than her neighbors. She is very knowledgeable about popular culture. She is messy and disorganized, but appears to like it that way. Having dropped out of community college prior to the start of the series, she is the only regular character to have lesser educational qualifications than Howard Wolowitz, who has a Master's degree. Despite her lack of education, she is insightful. While Sheldon routinely disparages both Penny's and Howard's educations, he occasionally acknowledges her intelligence and potential, something he never does toward Howard. He has also asked for her advice more than once regarding various social situations.
While usually appearing kind and cheerful, Penny does have a temper which has erupted on occasions, such as when Sheldon cleaned her apartment as she slept, when she confronted Howard over his "creepy" flirting, or when Sheldon "banished" her from their social group. Leonard has likened her to The Hulk when she gets angry, while Sheldon once said to his friend Stuart that she would "maul [him] like a rabid wolverine" if Stuart woke her up.
In addition to her temper, Penny's other main personality flaws are her selfishness, complacency and mild insensitivity. One major example of her flaws is when she had a fight with Leonard over the credibility of psychics, wherein he is prepared to concede to her and visit her psychic, but she is not, in turn, prepared to concede to him and read a book debunking psychics. On another occasion, she expects Leonard to play along with her story of "I whistled, you came running," when pretending that they got back together for her father's benefit, and is shocked when he does not. She laughed at the idea of Leonard ever breaking up with her in the fifth and sixth seasons until Sheldon's assistant Alex asked Leonard out, making Penny feel insecure. Her constant freeloading is another factor in this. Season 5 also revealed that Penny was a bully during her time at school. However, she seemed to be genuinely unaware of the hurt her actions had caused. Upon her realization, she attempted to make amends with those she tormented, with little success. Also, in season 6, she tricks Sheldon into telling her, Amy, and Bernadette the contents of a letter of Howard's that was sent to him by his father without any consideration of Howard's feelings. In the same season, while playing D&D, she leads the others on when she suggests Amy's and Sheldon's characters have sex in the game, not realizing she is mocking their relationship until after Amy leaves. An example of Penny's selfishness is prominent in the season 7 episode "The Mommy Observation," when, while playing a mystery game, she states her belief that Leonard would abandon his career if she became successful; she is surprised when he objects to this. She later confesses to Bernadette that her main regret is her lack of passion in life, which is why she struggles to take an interest in the geek culture that is such a big part of Leonard's daily life. On another occasion, she becomes insecure when Leonard makes a joke about her lack of romanticism.
A recurring theme is Penny's poor driving. She ignores speed bumps and stop signs, drives too fast, takes her eyes off the road, fails to service her vehicle regularly, ignores her check engine light, and has left her car's passenger side wing mirror "in a parking lot in Hollywood". She also hit a Mercedes in a parking lot and left without leaving a note. Leonard has, on several occasions, expressed terror at being in the car with her, although he is reluctant to tell her himself because of her defensiveness. Once her car dies, Leonard buys her a new one so she can go to auditions and pursue her dream of becoming an actress.
Other random facts about Penny have been revealed throughout the series. For instance, she has a Chinese character tattooed on her right buttock, which, according to her, means "courage", but is revealed to mean "soup" by Sheldon; however, Sheldon's fluency in Chinese is later demonstrated to be less than he thinks in "The Tangerine Factor". In season 5 she reveals that she has a tattoo of the Cookie Monster. She uses vanilla oil as perfume and snores loudly (especially when on her back). Early in the series, she claimed to be vegetarian, "... except for fish, and the occasional steak".
Interaction with Sheldon
A staple of the show's humour is Penny's awkward interactions with Sheldon, which are fuelled by the fact that they are almost polar opposites in terms of intellect and social aptitude, although they have very similar personalities.
In one episode, Sheldon tries to "improve" Penny, rewarding her with chocolate for what he considers "correct behavior", as in operant conditioning of lab rats. Although the two characters sometimes clash, and Penny is frequently irritated by Sheldon's obstinacy and lack of social awareness, she has developed a steady affection for him. She and Leonard occasionally behave as if Sheldon were their child, and Penny is very pleased whenever Sheldon acts tenderly towards her, such as hugging her or helping her when she is injured. Penny often calls Sheldon "sweetie", a term of endearment she rarely uses with other characters (a fact that Sheldon has himself pointed out), and Penny and Amy are the only principal characters who ever openly demonstrate their genuine fondness for Sheldon.
Evidence of Penny's affection for Sheldon is apparent in various episodes. Penny took care of Sheldon while he was ill and let him stay at her apartment when he was locked out of his; Sheldon lent her money when she needed it and took care of her when she dislocated her shoulder. Despite not being as well versed as the guys in geek culture, Penny has shown attention to what each of her friends likes. For instance, during a Christmas episode, Penny gave Sheldon a signed napkin used by Leonard Nimoy. In return, Sheldon gave Penny multiple baskets of bath products and then a long hug, to both her and Leonard's surprise. When Sheldon's World of Warcraft account was hacked and the four guys all backed down from the much larger hacker who also took Sheldon's Klingon Bat'leth, Penny kicked the hacker in the groin. In another episode, after Sheldon was forced to miss meeting Stan Lee as he had to appear in court on the same day, Penny took him to Stan's house so that he could meet him (which did not, however, go down well with Stan, especially when Sheldon mistook sarcasm for an invitation to come in and watch a Los Angeles Lakers game on television resulting in Lee taking out a restraining order against Sheldon). Following her breakup with Leonard, Penny took Sheldon along when she and some friends from work went to Disneyland, for which he was thankful. Penny enjoyed their time together, aside from him vomiting on her shoes. In the same episode, she noted that she takes Sheldon shopping for his linens. She has also helped Sheldon get over bumps in his relationship with Amy as in "The Shiny Trinket Maneuver". Penny is the only regular female character who has been on the show since its first season, although co-stars Mayim Bialik (Amy) and Melissa Rauch (Bernadette) have been promoted to main cast since their later appearance on the show.
Sheldon has also acknowledged that he likes Penny, although he claims this was only because he was forced to because Leonard "made him", and that Sheldon liking her was a "hard row to hoe". Despite Sheldon's overall friendly interaction with Penny, he does, on occasion, not always intentionally, insult her (usually on her intelligence). A running gag in The Big Bang Theory is Sheldon's frequent change of Wi-Fi password (as Penny uses Leonard and Sheldon's Wi-Fi as she does not have her own). Sheldon always changes the password to something instructing Penny to get Wi-Fi of her own, and is often insulting. So far, the passwords have been "Pennyisafreeloader", "PennygetyourownWi-Fi", and "Pennyalreadyeatsourfood.ShecanpayforWi-Fi".
Although Penny's personality usually contrasts to that of her nerdy friends, in the later episodes, their geekiness shows signs of having rubbed off on her, and she occasionally reveals these traits, either intentionally or unintentionally.
Penny was surprisingly good the first time she played Halo 3, camping at Sheldon's spawn location and killing him before he could move, which greatly aggravated him. In one instance, Penny was critical of the guys' interests in toys and collectibles, but Sheldon retorted by noting her collection of stuffed bears and other such childish things (Hello Kitty, Beanie Babies, My Little Pony, etc.). After a brief introduction to the game Age of Conan by Sheldon, Penny created a character named Queen Penelope. Penny became addicted, to the point of ignoring her friends and calling Sheldon at all hours of the day for advice. She finally overcame her addiction when she realized she had agreed to go on a virtual date within the game with Howard. After Alicia, a new tenant in the building, stole the boys' attention from her, Penny became jealous and tried to win over the boys again by making a physicist joke. To her own surprise, she even makes a casual reference to Star Trek while engaged in idle conversation, an indication of her growing geek awareness. In "The Electric Can Opener Fluctuation", when attempting to console Sheldon, she mentions events that occurred in the new Star Trek movie. In "The Wheaton Recurrence," Penny quoted, "Do, or do not. There is no try" while in bed with Leonard, and even mentioned she knew it was from The Empire Strikes Back. Leonard was pleasantly shocked that he was "in bed with a beautiful woman who can quote Yoda," and for the first time told Penny that he loved her, which then led to their breakup. In "The Apology Insufficiency," Penny had a chat with Sheldon and displayed knowledge of the Kobayashi Maru test, a plot device in Star Trek, impressing him. In "The Love Car Displacement", Penny ends up sharing Leonard's bed but tells him that, as far as romantic activities go below her waist, her "shields are up", alluding to the Star Trek defensive system. In "The Werewolf Transformation", Penny beats Leonard at chess despite the fact that she does not even know the standard names for the pieces. Leonard later admitted that Penny played chess like "Bobby Fischer". This may be a joke on the fact that Leonard is a terrible chess player. In "The Codpiece Topology", Penny references Schrödinger's Cat to her less-than-erudite date, Eric, and finds herself having to explain it to him. She learned of the thought experiment from Sheldon in "The Tangerine Factor". In "The Gorilla Experiment" Penny tries to impress Leonard by getting Sheldon to "teach her a little physics" in which Sheldon goes overboard and goes through 2600 years of history in physics. In the "The Beta Test Initiation", Penny correctly identifies that Leonard is describing beta testing when he uses a software development analogy to illustrate a point about their relationship. In season six, due to her relationship with Leonard, Penny begins going back to college, though she at first only reveals this to Amy and Bernadette because Bernadette finds her US History book, she also reveals to them that the reason she has yet to tell Leonard is because she did not want his help with the course or for him to "make a big deal about it", and due to Amy and Bernadette making her feel guilty for keeping this a secret from Leonard, she tells him and he confirms her accusations by rewriting her history paper for her, though she secretly has Amy and Bernadette do it for her, in which they help her get B- on the paper to guilt Leonard for trying to be helpful. She then tells Amy and Bernadette she wants to get an A on her next paper and they admit the reason they got her a B- was because they believed it would be "believable". In "The Bakersfield Expedition", Penny, Amy and Bernadette all get into an argument about how Thor's hammer Mjolnir works, and how someone could be worthy of it. In season 7's "The Proton Transmogrification," she alarms herself when she starts laughing at corny Star Wars-related puns.
Penny has shown that she had several run-ins with the law. It is stated that she has several parking tickets that have yet to be paid. She had also said to Amy and Bernadette that she and other students had once bullied a student who had better grades by tying her up in a cornfield and leaving her overnight. Although Penny considered it only a prank, Amy voiced her opinion that the incident made Penny a bully, to which Bernadette added, "and maybe a felon."
A recurring theme on the show is Penny's financial problems. This is prominently seen in "The Financial Permeability," when she finds herself behind on her bills, forcing her to borrow money from Sheldon, and becoming paranoid when the topic of it came up subsequently (even though he didn't really care about when she repays the loan). More subtle references are seen in the fact that she attempts to pay for her electric bill using a Starbucks gift card, an apology note and pictures of her in underwear, and for an expensive pair of shoes with a Texaco card. As a result of this, she often resorts to freeloading (a running joke is Sheldon's ever-changing Wi-Fi passwords as a result of her use of their Internet access), taking food from the guys' apartment as well as getting most of her meals paid for by Leonard. A reason for her financial problems may be her careless attitude toward them – she is, on occasion, known to cut back her hours at the Cheesecake Factory, and squanders any money she earns on shoes. In Season 7, she decides to give up her job at the Cheesecake Factory to pursue her acting career full time, with no thought about her already weak finances.
Not a lot is mentioned about Penny's family, other than her father Wyatt (also referred to in conversation with Leonard's mother as 'Bob') (Keith Carradine) trying to raise her like a boy, but on her accounts they seem to be a dysfunctional family. Her father appreciates Leonard as being by far the best man she has ever dated, and secretly encourages him to not give up on her. In contrast to all other characters, Penny and her father have not been imbued with a surname, thus far. Co-creator Bill Prady stated that Penny's last name will be revealed eventually. Despite this, executive producer Steve Molaro has since stated her surname will remain a secret.
In an early episode, Penny talked to Raj about her sister having shot her brother-in-law. In another episode, Penny accompanied the guys to the comic book store to shop for a gift for her 13-year-old nephew. However, in "The Boyfriend Complexity" (4–9), Wyatt (Penny's father) tells Leonard he wants grandchildren one day. In another episode, Penny has an unwanted guest, Christy, staying with her who had slept with her brother while being engaged to her cousin, saying, "she's kind of family." Christy knows Penny from back in Omaha and, according to Penny, she slept with nearly every man in the city, earning her the nickname "Whore of Omaha". While staying with Penny, Christy sleeps with Howard Wolowitz.
When Leonard's mother, neuroscientist and psychiatrist Dr. Beverly Hofstadter, chatted with Penny, she tearfully revealed some of her childhood issues, such as being called "slugger" by her father, whom she referred to as being named Bob, because he really wanted a son to play baseball with. This conversation affected Penny in such a way that she got drunk and almost ended up having coitus with Leonard (only to be interrupted by an out-of-place comment made by Leonard).
In the Season 5 episode "The Pulled Groin Extrapolation", after Penny quickly ate the last dumpling, Sheldon made a sarcastic comment to Penny saying, "I've seen pictures of your mother; keep eating," a comment that made Penny quite upset because this implied that Penny's mother might be overweight or obese. In episode 10 of season 5, Penny confessed to Bernadette that her mother smoked pot while she was pregnant with her.
Penny has mentioned having a brother on parole, who she says is "kind of a chemist." In "The Rhinitis Revelation" (5–6), she is more explicit in revealing that he is in the practice of cooking crystal meth.
Until the seventh season, Penny's main job was as a waitress in the local Cheesecake Factory, although in the first season episode "The Grasshopper Experiment" she trained as a bartender. It seemed that she occasionally picked up the bartending shift in the restaurant. In 2010, when actress Kaley Cuoco broke her leg, Penny was shown working as a bartender in several season 4 episodes to hide the cast on her leg.
Her work at the Cheesecake Factory, however, was actually meant to be a temporary job for her desired profession as an actress, although she has yet to find much success. Her expectations are somewhat high and naive at the beginning – she admits in season 2 that her plan was "waitressing for six months and then become a movie star", and her back-up plan was to become a TV star. She regularly goes to castings, but often ends up unsuccessful, or finding the role being auditioned to be quite different from what she expected, as was the case when she thought she was auditioning for a cat food commercial and it instead turned out to be a casting for a pornographic film. In the season one episode "The Loobenfeld Decay," she is cast in a production of Rent, and in "The Terminator Decoupling" she refers to another of her roles as "Anne Frank in a theater above a bowling alley". In the Season 5 premiere, frustrated over her lack of success as an actress (as well as damaging what was left of her relationship with Leonard), she briefly considers returning to Nebraska until landing a part in a commercial for hemorrhoid cream. In "The Monster Isolation", Penny is seen performing the role of Blanche DuBois in her acting class' production of A Streetcar Named Desire. In this episode Sheldon, who attended the show along with Leonard and Amy, is impressed with Penny's ability to memorize lines. In the seventh season premiere, she was revealed to have had a topless shower scene in a low budget horror film named "Serial Apeist" when she first moved to California, which she never thought made it to the Internet until Sheldon revealed that Howard looked it up right after they met her. Despite the hardships she encounters along the way and having to revisit her ideas about acting, Penny is tenacious in her pursuit of her dream profession. Despite expressing occasional irritation with her waitressing job, she usually kept up a cheerful front, held down the job and got on well with others working at the restaurant. She originally met Bernadette at the Cheesecake Factory.
In the season seven episode "The Hesitation Ramification," Penny believes she has finally found stardom when she lands a brief role in NCIS. She is devastated when her scene is cut, but later decides it is time to focus solely on acting; she quits her job at the Cheesecake Factory to devote herself to it full-time.
Despite usually going to her neighbors for technical assistance when she has problems with her computer, Penny does have some mechanical skills of her own. When she was a child, she rebuilt a tractor engine on the farm where she grew up and competed in a junior rodeo.
Unlike the rest of the main characters, Penny is very outgoing and assertive, and has many romantic relationships over the course of the series. She often dates and in one way or another all the guys have gone to her for dating advice. In the fourth season opener, Sheldon uses probability and extrapolation calculations to estimate that Penny has dated "193 men... give or take 8" since she started dating at age 14, and slept with "30.96" of them (rounded up to 31). Penny strenuously denies it was ever that many, but her subsequent expression indicates shock and resignation to Sheldon's correct estimate. Amy asks Penny in the same conversation if, in light of her sex partners, she considers herself a slut, Penny responds unsure, "No. No. ... No?"
In the first episode of the series, Penny moved in across the hall from Leonard and Sheldon because of her recent split from her boyfriend, Kurt, after living together for four years. She said she still loved him even though he cheated on her. Kurt makes further appearances in the show trying to get back together with Penny just to use her, and is usually confronted by Leonard.
From the beginning, Leonard's infatuation with Penny becomes the major force that drives the series. Howard also shows interest in her (primarily sexual), but he is always rejected abruptly due to his unsettling approaches. Raj is secretly attracted to Penny as well, but does not interact with her a lot due to his inability to talk to women unless he is drunk. Although Penny occasionally teases Raj for his inability to speak to her, she is sympathetic and kind towards him, and as with Sheldon, she almost always overlooks his idiosyncrasies and appreciates that his intentions are good.
In an early episode, Penny described her approach after a failed relationship: she picks up an attractive man to have rebound sex with over the course of a 36-hour weekend, then leaves him.
In the first season finale, Penny broke up with her boyfriend after he posted intimate details about their private life on his blog. This gave Leonard the opportunity to ask her out on a first official date. Although the date was successful, Penny became worried after she lied to Leonard about graduating from community college (it is mentioned in a later episode, "The Cohabitation Formulation", that she was enrolled in one, but dropped out). When Sheldon asked her why she lied, she said she did not want Leonard to see her as a "stupid loser". Leonard eventually learned the truth from a drugged Sheldon but made matters worse when he tried to encourage Penny to enroll in Pasadena City College. Penny interpreted his suggestion as an insult to her intelligence and did not want to see him again.
Some time after, Penny's introduction to Leonard's mother, Dr. Beverly Hofstadter, caused Penny and Leonard to seek comfort in each other. They nearly have sex, but when Leonard comments in bed that she was attracted to him because of a psychological need to be closer to her father, her revulsion at this causes her to rebuff him.
Afterwards, Penny dated Stuart, from the comic book store, but their dates did not lead to a relationship. The first time, Penny and Stuart were interrupted by Sheldon who argued at length with Stuart over whether Dick Grayson or Jason Todd should be Batman's successor, successfully putting Penny to sleep. On another occasion, when Penny and Stuart were kissing, Penny mistakenly called him "Leonard".
It was in the second season finale that Penny finally showed strong romantic feelings for Leonard. When she discovered that Leonard, Sheldon, Howard, and Raj would be spending three months at the North Pole for a scientific experiment, she became sad and gave Leonard a Snuggie and an unusually long hug, which Leonard described as lasting for "five Mississippis". Leonard asked her what all this attention meant and she lightly dismissed it. After Leonard left, she sighed and said to herself that it meant that she didn't want him to leave.
In the third season premiere, after the guys returned from the expedition, Penny kissed Leonard right away when he arrived at her door, ending the episode with both Leonard and Penny in Penny's bed.
Initially, Leonard and Penny felt uncomfortable with their new relationship, and they agreed to remain only friends, but were unable to maintain this resolution and remained a couple. Their relationship soured, however, when Leonard told Penny he loved her for the first time, and an unsure Penny simply replied, "Thank you." This tension was heightened due to comments made by Wil Wheaton to Penny about regretting having been in a similar situation. Though Wheaton's comments were likely fabricated, since he was trying to distract Penny during a bowling match against her and the guys, she took them seriously and this eventually caused her to break up with Leonard. However, they remain friends and even sleep together once after breaking up after Penny gets drunk following a bad date with Zack Johnson. She realizes Leonard ruined her ability to tolerate and date unintelligent men. However, this only caused more confusion about the status of the relationship for Leonard.
In the fourth season, Penny reveals to her friends Bernadette Rostenkowski and Amy Farrah Fowler during a "Truth or Dare?" game that she has still not moved on from Leonard, though this is not the only time that she hints about her feelings. This was further implied in "The Justice League Recombination" when she told Leonard that he was one of the reasons New Year's Eve became unpleasant, and the two exchange awkward looks as Penny kisses Zack (with whom she had reunited after their breakup in order to have a date on New Year's Eve). In "The Love Car Displacement", Penny accompanies the guys, Bernadette, and Amy to an academic conference in Big Sur. She and Leonard share the same hotel room for a time and they almost have sex until Raj walks in on them. The next day, bored with the conference, Penny accepted a ride back to Los Angeles from Professor Glenn, Bernadette's tall and attractive ex-boyfriend. When Raj's sister, Priya, returns in the episode "The Cohabitation Formulation", Priya and Leonard resume their old relationship – they had dated in the past whenever she was around. Penny appears to be initially accepting of their relationship, but is later discovered by Amy to be heartbroken over it. In the following weeks, she began to realize that she still has strong feelings for Leonard.
In the Season 4 finale, Penny reveals to Raj that she regretted breaking up with Leonard. However, even though she and Raj both agree to be friends, they get drunk and wake up in bed together, apparently both naked, the next morning. Leonard, Sheldon, and Howard discover Penny and Raj walking hurriedly out of the bedroom, an apparently naked Raj wrapped up in a blanket next to Penny with her messed-up hair, clutching her heels – implying that they just had sex. In the Season 5 premiere, it appears that Raj and Penny had intercourse, but Raj confides to her that they had not consummated their encounter, prompting Penny to refer to Raj as "Quickdraw" because of that. She spends the rest of the episode with Amy, avoiding the guys in an attempt to apologize for her encounter with Raj.
In "The Ornithophobia Diffusion" Leonard and Penny go on a platonic date as friends, but after Leonard expresses the opinion that he does not have to pay for everything or defer to her because they are not a couple, they end up bickering and sabotaging each other's attempts to socialize with members of the opposite sex. Penny realizes that she finds Leonard's more assertive demeanor attractive, but when he regresses to groveling in order to have sex with her, she rebuffs him.
On the spur of the moment in "The Recombination Hypothesis", Leonard asks Penny out on a date after he imagined what getting back with her might be like. Their real date ends successfully and they agree to take their relationship slow in "The Beta Test Initiation". They hit a few rough spots at the beginning of the episode, but then learn to accept what they each want and make up afterwards. When Leonard asks how the beta test (referring to their relationship status) was looking, she replies, "it's looking pretty good" and they share a kiss. In "The Werewolf Transformation" Leonard teaches Penny to play chess and Penny beats him even without learning the standard names of the playing pieces.
During her renewed relationship with Leonard, she has dismissed comments about him ever leaving or dumping her or about worrying about his unfaithfulness around other women and strippers as in the episode "The Stag Convergence". After Penny suggested having sex in "The Launch Acceleration", Leonard breaks the mood by proposing to her. They later meet and Penny does have the courage to tell him "no" and not break up with him as she did two years previously when he told her that he loved her. They finish season 5 watching Howard being launched into space while holding hands to comfort each other. With the start of season 6, Leonard wants a reluctant Penny to define their relationship in "The Date Night Variable". With her girlfriends, she wonders if she is really in love, but cannot quite discuss it with Leonard, in "The Decoupling Fluctuation." Also, in "The Holographic Excitation," she reveals that she has a selfish perception of how a relationship works – saying that Leonard's job is "to make her happy", and her job is "to let him make her happy."
In the first episode of Season 6, "The Date Night Variable," Penny and Leonard are having a 'stay-at-home date' at Leonard's apartment when Raj shows up (having been ejected from the date between Amy and Sheldon where he was a third wheel). He inserts himself into Penny and Leonard's discussion of where their relationship is headed. When Leonard complains that Penny has yet to say "I love you" to Leonard, Raj attempts to get her to say it, causing Penny to eject him from the apartment.
In "The 43 Peculiarity," Leonard becomes jealous of Penny's classmate, an attractive Englishman and attempts to scare him off. When Penny learns of this, she is angry with Leonard, who fears that he has again damaged their relationship. Leonard casually seeks advice from Alex, Sheldon's attractive graduate student assistant, while having coffee in the University cafeteria. Alex flirts with Leonard, though he is seemingly unaware of her attraction to him, laughing it off. At the end of the episode, Penny and Leonard encounter each other in the hall outside their apartments, where Penny expresses her frustration with Leonard's jealousy saying, "You're the one I'm with, and you know that I love you." Both then realize that this is the first time she has declared her love for him openly, and Leonard asks if they should act "like it's no big deal." Penny tells him that they must do so, or she will start crying and so will he. They part awkwardly as Penny has to go to work. Inside his apartment, Leonard smiles and says to himself, "She loves me," but then gets a text from Alex telling him that she would like to get together again, though Leonard still does not realize her intent is to be more than just friends. In "The Egg Salad Equivalency" Penny learns that Sheldon's assistant Alex asked Leonard out to dinner and she did admit to Leonard her insecurity about their relationship. In "The Bakersfield Expedition" Leonard says that he loves Penny, but he cannot share his Comic Con make-up with her which he is using to dress as Capt. Jean-Luc Picard of Star Trek: The Next Generation. After another blow-up with Sheldon, Leonard tries to move in with Penny in "The Spoiler Alert Segmentation" however she is not ready yet for them to live together. In "The Tangible Affection Proof", Leonard again tries to propose to Penny on Valentine's Day and she ends it quickly. She admits to being very happy with Leonard, but she has commitment issues. The thought of being married "forever" really "freaks" her out. Leonard then tells her that when she is ready to get married, she can propose to him. In "The Bon Voyage Reaction", Penny sends Leonard off to Europe for the summer, missing him, but secure in their relationship.
In the Season 7 episode, The Thanksgiving Decoupling, Penny reveals that she got drunk with Zack in Las Vegas and they had one of those 'little fake weddings', which the gang points out to be real. Under pressure from Leonard, Penny quickly has the marriage annulled. In "The Hesitation Ramification"; Penny is frustrated about her acting career and while inebriated proposes to Leonard who does not know how to answer a tipsy girlfriend. She gets even more frustrated and leaves though next week in "The Occupation Recalibration", she admits that Leonard did the right thing.
By season 5, Penny had formed strong friendships with Doctors Amy Farrah Fowler and Bernadette Rostenkowski, and the three have formed their own group, spending time in Penny's apartment, going out together and supporting each other emotionally.
No reason has ever been given why Penny tends to be withdrawn about her inability to commit to a relationship though she does admit it in "The Tangible Affection Proof". She does however, overcome her inability to commit in the penultimate episode of season 7 "The Gorilla Dissolution" where she and Leonard are engaged.
In the original, unaired pilot of the series, the conception of the female lead was very different. She was called Katie, and was envisoned as "a street-hardened, tough-as-nails woman with a vulnerable interior". Sheldon and Leonard would "approach her with honesty, to draw the real, sensitive Katie out". The role was played by Amanda Walsh. However, the test audiences reacted to the character negatively, seeing her as too mean. Because of this, the character was changed, and the role was recast.
Tom Jicha of the South Florida Sun-Sentinel says of Cuoco, "Her character had the potential to be a bimbo but she has developed it into a fully fleshed-out woman, who isn't as book-smart as the other characters but is wiser in so many ways. She's also a great straight person, who can get off zingers of her own".
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- "The Nerdvana Annihilation". The Big Bang Theory. Season 1. Episode 14. April 28, 2008.
- "The Barbarian Sublimation". The Big Bang Theory. Season 2. Episode 3. October 6, 2008.
- "The Dead Hooker Juxtaposition". The Big Bang Theory. Season 2. Episode 19. March 30, 2009.
- "The Extract Obliteration". The Big Bang Theory. Season 6. Episode 6. November 1, 2012.
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- "The Dumpling Paradox". The Big Bang Theory. Season 1. Episode 7. November 5, 2007.
- "The Maternal Capacitance". The Big Bang Theory. Season 2. Episode 15. February 9, 2009.
- "The Rhinitis Revelation". The Big Bang Theory. Season 5. Episode 6. October 11, 2011.
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- "The Middle Earth Paradigm". The Big Bang Theory. Season 1. Episode 6. October 29, 2007.
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- "The Monopolar Expedition". The Big Bang Theory. Season 2. Episode 23. May 11, 2009.
- "The Electric Can Opener Fluctuation". The Big Bang Theory. Season 3. Episode 1. September 21, 2009.
- "The Jiminy Conjecture". The Big Bang Theory. Season 3. Episode 2. September 28, 2009.
- "The Wheaton Recurrence". The Big Bang Theory. Season 3. Episode 19. April 12, 2010.
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- Paige Albiniak, "For Dramas, Expect New Faces," Broadcasting & Cable, June 13, 2011.