"I'm not asking much. It's not as if I want to be a rich beautiful, glamorous movie star. Or even a well-liked beautiful, glamorous movie star. I just want to be a beautiful, glamorous movie star for its own sake."
— Passionella, The Apple Tree
Being beautiful has many benefits: respect, love, friendship, control, and ultimately power. It can be the power to improve one's life, the power to destroy others...when you're beautiful, the world is your oyster.
What exactly is beauty, anyway?. Each person has a different concept on what beauty is, but that doesn't mean people won't agree on what or who is beautiful. Beauty is often in the eye of the beholder, but that doesn't mean it's not something some people would give anything to have. Likewise, those who are already beautiful typically want to stay that way.
This trope comes into play when a character's quest for beauty - either achieving it or maintaining it - becomes their primary motivation or defining characteristic. For when it's a villain(ess)'s goal, see Fairest of Them All.
Contrast True Beauty Is On The Inside.
Eureka tried makeup in episode 36 of Eureka 7 upon realizing the importance of beauty (she was somewhat disfigured at the time, having sores on her cheek, chin and forehead). Too bad the result backfired.
In the first chapter of Code Name Sailor V Minako expressed this wish. Cue Artemis offering her the powers to become Sailor V advertising the 'incarnation of the goddess of beauty' part of the package (she would have probably accepted them immediately had he not walked on her while she was naked).
In Jules Feiffer's Passionella, a chimney sweep wishes she could be a "beautiful, glamorous movie star." Then a friendly neighborhood godmother appears on her TV set and grants her wish—but only from The Mickey Mouse Club to the Late Late Show.
In Precious: Precious Jones (an African-American Fat Girl) has a horrible life in every aspect. Her life is so bad that her only way to bear her pain is escaping reality through fantasies. The poor girl's self-esteem is so down that when she looks at herself in the mirror (instead of seeing her true reflection) she fantasises that she is a beautiful white model pictured here◊.
In The Stainless Steel Rat, Angelina began life as an extremely ugly child, and grew up hating the world around her. Too poor to afford the extensive surgery that could change her looks, and cursed with an extremely keen mind that allowed her to see the injustice of her life, the young girl turned to a life of murder and crime to get the funds she needed. Eventually the adult Angelina had surgery that transformed herself into a true beauty - on the outside; on the inside she had become as callous and psychotic as they come.
In Bruce Coville's book Jennifer Murdley's Toad (part of the Magic Shop series), the lead character is a truly unattractive young girl. At one point when she was younger she saw a commercial for Barbie on TV and started crying. Subverted at the end of the novel, when Jennifer is shown a magical image in a mirror of how the witch can make her beautiful. All she has to do is hand over the magic toad. She destroys all of the mirrors, knowing she can never be that girl.
In The Dresden Files some vampires come off this way. Revealing their monstrous form results in a pretty big emotional hit for them.
In The Picture of Dorian Gray, Dorian unwittingly makes a "pact" to remain forever young when he sees his portrait. He becomes immune to aging and body damage, and instead his portrait receives the damage.
In Caroline B. Cooney's The Return of the Vampire, the plain female protagonist wants to be beautiful above all else because she knows it'll make her popular and loved by her classmates. The eponymous vampire grants her wish by draining the Alpha Bitch of her beauty and transferring it to her. She undoes it at the end when she realizes she doesn't need beauty and that the girl she stole the beauty from needs it more than she does.
Aza of Fairest wants most of all to be beautiful, having been looked down on or shunned by others because of her odd looks. She wants it so badly, in fact, that she tries reciting a spell to make her beautiful and ends up with a solid marble toe for it and is enticed into drinking a beauty potion by a Magic Mirror. The potion wears off when she destroys the mirror (as it housed an evil spirit who was manipulating the Queen), and she learns to accept the way she looks.
This is one of the main reasons why Bella Swan wants to become a vampire. Even though every male around her seems to find her attractive and interesting no matter what the reader may think.
Agnes Nitt from the Discworld books has some bouts of this, wishing in Maskerade that she'd been born with good looks instead of great hair, a wonderful personality, and an ability to keep a cool head in a crisis. Other times you'd get the feeling she'd be satisfied with being respected even if she's nottraditionally beautiful.
Live Action TV
In Yo Soy Betty La Fea, the eponymous ugly character, Beatriz "Betty" Pinzon, is unlucky to be an ugly girl in the world of fashion. Despite being the most intelligent woman in the show, she was constantly mistreated by most people just because of her looks. Her ugliness was a daily hardship she had to face from the beginning. Not to mention nobody wanted to hire her because of being ugly. She wanted to be beautiful because she fell in love with her handsome boss, Armando, and because she had self esteem problems. She actually had a "makeover"; however, contrary to the typical makeovers in Hollywood, this makeover didn't make her Beautiful All Along... her new image reflected how more much more confident of herself she had become despite being as ugly as always.
In Wicked, Elphaba originally wished to meet the Wizard so he could undo her green skin and make her beautiful, among other things.
A variation of this is found in BioShock. The once-renowned plastic surgeon Dr. Steinman — who believes beauty is a "moral obligation" — slips gradually into insanity until he becomes a full-fledged psychopath, and embarks on a one-man quest to create "perfection" in order to appease his goddess, Aphrodite. Seeing as how, in his madness, Steinman considers asymmetry to be the path to true beauty and is the self-proclaimed "Picasso of surgery", you can imagine the gruesome implications this has for his unfortunate patients for yourself.
Daisy of Bittersweet Candy Bowl is jealous of the male attention that Tess and Lucy receive, and assumes it is because she isn't as physically attractive as her friends. When a boy finally pays attention to her, she is happy even though he is a jerk - and even after he (seemingly) tries to rape her, she still has feelings for him, though she is smart enough to stay away from him.
Shrek: Princess Fiona is a very beautiful girl, however she is cursed to transform into an ogre by night. She describes her ogre self as very ugly. Shrek himself thinks otherwise. At the end she breaks the curse with a true love kiss, however not in the way she expected: she is now stuck in her ogre form and while she remarks "I don't understand. I'm supposed to be beautiful." Shrek responds with: "But you are beautiful."] Although she seems less bothered by turning into an ogre and more upset by the fact that princesses aren't supposed to look like that. After Shrek confesses his love to her, she doesn't care and, indeed, freaks out upon turning back to her human self, in the sequel.
In Cinderella 3 one of the ugly step sisters of Cinderella wants to be beautiful, thinking she will not be happy without beauty. She uses a magic wand to become an exact copy of Cinderella. At the end she learns to accept herself as she really is, and look for someone that will love her for what she is.
Kids Next Door: In "Operation C.A.R.A.M.E.L" it is revealed the reason Heinrich Von Marzipan◊ hates Numbuh 5. He made a magic ritual and lost his most valued trait: "beauty". He thought he was cursed forever. However thanks to Numbuh 5 the curse was broken. Instead of becoming a beautiful boy it was revealed that his true form was that of a beautiful girl called Henrietta von Marzipanpictured here◊.
In Danny Phantom, the episode "My Brother's Keeper" has the villain feed off teenage depression in order to remain beautiful. She later does it again in another episode by trying to steal perfect qualities of their best attributes to give herself a perfect human body.