Missy Cooper

Melissa "Missy" Cooper is Sheldon's younger sister, who is ironically the direct opposite of her brother in many ways (besides being female, she is not above physical confrontation, is very charming and amicable, as well as possessing a very cheeky sense of humor). She is the sister-in-law of Amy.

Young Sheldon
Missy is a main character on Young Sheldon. She is portrayed as a bratty 9-year-old who fights with Sheldon for attention from their parents. Sheldon gets all the attention because of his intelligence and for starting high school at such an early age. Missy is disrespectful and contemptuous towards Sheldon, wishing him to disappear and even showing signs of optimism when her parents considered getting a divorce, hoping she could get away from Sheldon and part with her mother. She relished seeing Sheldon have bad luck and being lonely at school. She and Sheldon shared a bedroom. In "Potato Salad, a Broomstick, and Dad's Whiskey", she successfully pulled a splinter out of Sheldon's finger using toy tweezers though she only did it to make Sheldon stop complaining rather than from a change of heart.

Unlike Sheldon, Missy displayed little to no interest or aptitude in schoolwork, finding it challenging, especially math. She preferred to watch TV the whole time she was home such as ALF, DuckTales, and Looney Tunes and ignored her homework. The fact that she chose not to prioritize studying could foreshadow her ultimately having to work as a Fuddruckers hostess for a living while both her brothers achieved middle to upper-class standing as a physicist and tire entrepreneur.

Missy has a sweet tooth for candy. Her parents spoiled her on a daily basis by buying her sweets and letting Missy watch TV all day long.

The Big Bang Theory
Missy's appearred in "The Porkchop Indeterminacy" (S01E15). When Leonard, Howard, and Raj find out Sheldon has a sister and that she is quite attractive, they fall over each other trying to get her attention. Raj is inspired to begin taking an experimental medication to overcome his pathological shyness.



When Sheldon states that he'll decide who Missy dates, she decides to speak with him privately. Sheldon reveals to Missy that she has the potential to produce a second Sheldon, even a second Sheldon that is, "taller, smarter, and less prone to freckling, a Sheldon 2.0, if you will"). Missy tells him that she is fine with him acting like a brother who cares about her, but if he tries to tell her who to sleep with in her bed, they are gonna go "round on round" like they did when they were children. This flies over Sheldon's head and he suggests Missy donate her eggs and cryogenically store them until he finds the right sperm donor to fertilize them before implanting them into her body. By this act, he suggests, "everybody wins". Missy then begins painfully squeezing her brother's testicles until he withdraws the statements.

Missy finds more of an ally with Penny, who has become slightly immune to the quartet's geekiness, as well as helps Missy extricate herself from them and lets Missy hang out in her apartment. Leonard, Howard, and Raj all knock on Penny's door to ask Missy out, but they fail in the end. When Raj goes to ask her out, she says that she was waiting for him to show up and calls him a cutie-pie, but Raj's medication starts wearing off so he is unable to talk to her and leaves looking sad.

Before she leaves, Missy tells Sheldon that she is proud and reveals that she brags to her friends about her brother "the rocket scientist", which sparks him to correct her that he's a theoretical physicist, noting the difference. After she leaves, Sheldon mutters back to his apartment saying that being a rocket scientist is beneath him.

Sheldon mentions her in "The Jiminy Conjecture" (S3E02), when Howard, Sheldon, and Raj are trying to capture Toby/Jiminy and distinctly hear cricket chirping down the apartment building's elevator shaft. As tensions rise, Howard threatens Sheldon with, "Don't push me, Sheldon. I may be small, but I took Kung Fu when I was 13, and I remember a good deal of it," Sheldon responds with, "Oh really? Well, I grew up with an older brother and a very contentious twin sister and I believe I could easily best you in any physical confrontation, be it noogies, swirlies, or the classic 'Why are you hitting yourself?'"

Sheldon's family pedigree, depicted briefly in "The Cruciferous Vegetable Amplification" (S4E02), shows an older brother as well as his twin sister.

In "The Cooper Extraction" (S07E11), Missy is about to give birth to a baby in Texas. Since her husband is recovering from a terrible motorcycle accident, Sheldon has to go back to look after her. She does not appear on screen in this episode, only a scream as she gives birth is all that is heard from Missy.

In "The Fortification Implementation" (S8E20), Sheldon tells Amy that his brother and sister built forts in the living room and wouldn't let Sheldon in, which he hated so much.

In "The Maternal Combustion" (S8E23), Sheldon tells Leonard's mother Beverly that his brother and sister are mouth breathing idiots.

In "The Matrimonial Momentum" (S9E01), Mary Cooper mentions that since Missy is married and their brother is dating a "whore", she wants Sheldon to keep her grandmother's ring which she gave Sheldon for Amy.

In "The Meemaw Materialization" (S9E14), Sheldon reveals that he got an iPhone for Meemaw Constance as a Christmas present but she is completely unaware of it. He had Missy slip it inside Meemaw's luggage when she flew in from Texas so Sheldon could keep track of her location.

In "The Celebration Experimentation" (S9E17), Sheldon says that Missy and her friends used to torture him on their birthday and on their 6th, tricked him into believing that Batman was coming.

In "The Sibling Realignment", according to George after their father died, their mother was a mess and Missy was no help because she was just a "dumb teenager".

In "The Bow Tie Asymmetry", Missy attends the wedding of her twin brother appearing physically for the first time in ten years. She is currently pregnant and separated from her husband. She is happy about the separation, but not thrilled about the baby. Amy tells her how happy she is to finally have a sister.

Family

 * Father: George Cooper Sr.
 * Mother: Mary Cooper
 * Brother: George Cooper Jr.
 * Twin Brother: Sheldon Cooper
 * Grandmother: Meemaw
 * Grandfather: Pop-Pop
 * Uncles: Carl, Edward, Uncle Roger; There is another uncle who gave children gifts like Santa and was not arrested in Oklahoma for his actions.
 * Aunt: Aunt Ruth
 * Husband: Unnamed (currently separated)
 * Daughter: Cher
 * Daughter: Unborn (as of "The Bow Tie Asymmetry")

Trivia

 * She calls Sheldon by his nickname, "Shelly", as does their mother.
 * When they were kids, Sheldon turned her into a furnace for baking ceramic  substrates for homemade  to make a robot to defend his room from her.
 * Despite their differences, Missy is very proud of Sheldon and his accomplishments, and tells people Sheldon is a "", which he felt deeply offended by because he is a theoretical physicist, which he views as much more prestigious and tells her that she might as well tell people that he is a toll collector at the.
 * When Leonard offered Missy to stay with them, she reveals that Sheldon does not like company and he used to send his imaginary friends home at the end of the day when he was a child: he denies it, saying that they were "imaginary colleagues".
 * She once had a dog who made strange noises, which she later had put down.
 * It is revealed in the Pilot that she is a hostess at when Sheldon is expressing concern of "committing genetic fraud" about donating sperm at a high-IQ sperm bank ("I have a sister who has the same basic  mix who hostesses at Fuddruckers.")
 * In the episode "Summer Sausage, a Pocket Poncho, and Tony Danza" of Young Sheldon, it was revealed that her full first name is Melissa, Missy being a nickname.
 * Incidentally, Melissa is the first name of the actress who plays Bernadette, Melissa Rauch.
 * Her mother dismisses her as "dumb as soup" in "The Luminous Fish Effect": though she is likely nowhere near as intelligent as her brother, she seems witty, presentable, and funny. Though Sheldon also mentioned in "The Cooper Extraction", it took Missy six years to graduate from high school, implying her mother's comment about her intelligence isn't wholly inaccurate.
 * When she first meets the gang at Caltech, she tells them that she spent nine months with her legs wrapped around Sheldon's head.
 * She used to obligate Sheldon to do whatever she wants by pressing his testicles. As an adult, she still does it, but now when she gets mad at him when he suggests some absurd ideas, and if he is acting ridiculously stubborn.
 * Sheldon considers her, with his help in choosing a proper and approved-by-him mate, the future mother of a "Sheldon 2.0". As he considers himself to be a "superior genetic mutation", and with Missy being his twin sister (though still also "mediocre stock"), her DNA has great potential in producing a new version of her brother, likely even superior to him. She, however, doesn't see it that way.
 * She is taller than Leonard, Penny, Raj and Howard, like her brother.
 * In the episode "The Cooper Extraction", it's revealed that Missy got married and was having a baby girl.
 * In one episode, Sheldon mentions that she had a guinea pig called Snowball, who ended up bursting into flames when Sheldon put him in a home-made CAT scanner.
 * Her husband's name and her daughter's name are both unknown.
 * She finally reappeared in the season 11 finale, at Amy and Sheldon's wedding. This was her first physical appearance of her and her actress Courtney Henggeler in ten years.
 * In "The Bow Tie Asymmetry", it's revealed that she is pregnant with her second child and she and her husband are separating.
 * As shown by her sarcastic reply upon being congratulated her second child, she isn't quite thrilled about her second pregnancy.
 * Raj is shown to be delighted upon hearing Missy's separation from her husband. What with him having conquered his selective mutism and experience in dating, and now with Missy single, there is an indication that a possible romance may start between them.