Though it isn't explicitly stated, a large portion of the backstory goes into showing why Guts is such a hardened (and therefore exceptional) warrior. Most of his life has been misery heaped on tragedy, forging him into an inhumanly durable person.
On the other hand Casca most definitely did NOT become stronger from her misery. After all, this trope only works when applied moderately, not in excessive doses. It says a lot about the series and the setting that Guts' misery can be considered 'moderate'.
Dark Magical Girl Fate Testarossa became the kindest and easily the most heroic character of Lyrical Nanoha series because she was abused and abandoned as a child, resolving to let no more children share her fate on her watch. On the other hand, in the Battle of Aces, Arf suggests that Fate could have gone down a darker path like her Evil Counterpart Material L did if not for meeting Nanoha and the others.
Kujira Kurokami from Medaka Box based her life on the saying, "Something amazing can only be made after seeing hell," believing that any happiness would keep her from creating her best work. Thus, she forced this trope on herself, even going so far as to run away from her well-off family, change her name, hide her face, and erase her memory.
Monkey D. Garp in One Piece seems to subscribe to this theory, as he subjected Luffy as a child to many horrible trials, such as being tied to balloons and let fly away, or being left in the jungle at night with all the animals. It did seem to succeed in helping forge Luffy as something more than normal...
Yu-Gi-Oh!: Gozaburo Kaiba, adoptive parent to Seto, was abusive to him on a daily basis in order to prepare him to be ruthless in the business world. Needless to say, he succeeded.
Played straight andsubverted in Naruto. Several people, the main character included, are better people specificially because they can empathize with the pain others are feeling. However, the main character makes it very clear that endless suffering is like drowning, and you can only last so long without someone pulling you up for air. The jinchuuriki who have someone supporting them turn out well, like Bee and Naruto, but the ones like Gaara who have nobody....don't turn out well. And there are cases like Haku and several members of the Sound, who suffered so much that a single act of kindness or even neutrality made them devote themselves to people just to feel needed, even when they knew they were just being used as tools.
"You live a life like mine, you end up with a pocketful of regrets. A good regret gives a man character, if you ask me. I didn't get to be this handsome and laconic through clean living."
Punchy stops Dead Kid Fred from committing suicide. Later, it's revealed that he wished he hadn't gotten to him in time, because having a death on his conscience like that would've made people take him more seriously as a hero - would have made him a better hero. This may have something to do with the fact that the murder of his sister sparked his career as a superhero to begin with.
Duke more or less exhibits the trend, as well, being probably the nicest of the main characters while having probably the worst home life.
This was the rationale of The Flash villain Zoom, who attempted to murder Wally West's wife, believing that West needed to suffer personal tragedy in order to become a better hero.
Over the course of Art Spiegelman's Maus, Spiegelman's father Vladek states several times that, although his time in the concentration camps was horrific beyond measure, he learned several skills that would serve him well later in his life.
In the Girls und Panzer fanfic, Off The Path, Shiho discusses this trope in her POV chapter, titled "Sacrifice", defending her approach to teaching tankery and raising Miho.
It may be overly simplistic to say something like "misery builds character," but the decisions most necessary for success- in goals you choose yourself, as well as those chosen for you- are seldom the easiest or the most pleasant. It often takes an adult to realize this, and the related idea that there are things greater than your own desires and feelings, when a child cannot.
Penny: Without that show I have nothing! Prudy: Having nothing builds character!
Motorama: A boy with an injured eye will lose his sight if it isn't operated on.
Darrell: I guess he'll have to lose his sight. [snip] You see, loss builds character.
Professor Thomas: The government cut the electricity. Sylvia: Why? Professor Thomas: To build national character!
A Gentle Art:
Lance: Pain, they say, builds character... and you, my dear, are about to have more character than you know what to do with.
Major Payne did this deliberately to mold his students into a cohesive unit. The Guidance Councilor thinks this was an incredibly cynical plan. But by God, it worked! This became less "making them suffer to be better," which he himself went through, but "making them suffer together equally, and have a shared target of ire," a very common tactic among Drill Instructors, Sports coaches, etc. And yes, it is damned effective if done right.
The Matrix: Agent Smith believes this to be humanity's hat, citing humanity's refusal to accept the first utopic Matrix as real:
"Some believed that we lacked the programming language to design your 'perfect world,' but I believe that human beings as a species define their existence through misery and suffering."
A central theme throughout The Dark Knight Saga is Bruce overcoming increasing adversity and hardship to become stronger. Interestingly it also shows a darker side to this trope in that many of the villains he faces have also been forged by past tragedy and suffering.
Batman Begins has Bruce endure the Training from Hell in order to become Batman. All fueled by the death of his parents and personal vengeance denied to him. His mentor Ducard was similarly motivated by the loss of the woman he loved though he chose a more extreme path.
In The Dark Knight Rises, Bruce becomes stronger from being forced to watch Gotham as descends into anarchy, while he's trapped in a Moroccan prison half a world away, unable to do anything about it.Lampshaded when Miranda Tate says this, nearly verbatim, to Bruce Wayne. Despite the baddies' familiarity with this trope, Bane in particular is utterly shocked when Wayne crawls out of the hole, and manages to destroy them both. It's also - possibly - why Wayne has recovered enough from his childhood trauma to finally quit angsting and enjoy life in the end.
In the movie version of Holes, the staff at Camp Green Lake claim the juvenile delinquents are forced to dig holes because it builds character. The real reason is there's a fortune buried somewhere in the dried up lake bed and camp was created to try to find it.
A couple of deleted scenes in Bruce Almighty ended up expanding on the consequences of Bruce granting the wishes of every person who prays to him, with God showing Bruce a couple of the people who's prayers he answered and how, though he's made them happy now, they'll actually be worse off in the long run.
God: Triumph is born out of struggle, faith is the alchemist. If you want pictures like these, you'll need to use some dark colors.
A deleted scene in Rocky Balboa has Rocky talking about how as a kid he would stare into streetlights without blinking and squeeze a ball in his hand until it was unbearably painful. He did this to make himself used to being uncomfortable and tolerate pain better. It paid off big time.
The Bible: The Apostle Paul discusses this in Romans3-5, where he notes that suffering builds endurance, endurance builds character, and character builds hope. Considering the time period, he and many of the other Christians that were physically tortured and martyred for their faith knew what they were talking about from many experiences they could count by the lashes on their backs.
White Tower initiates suffer this trope. They must do all their chores by hand, without using their mystical powers, because menial labor is misery that builds character.
Black Tower trainees invert both the trope and the above example. They must use their mystic powers for everything, including lighting lamps and cooking dinner— so when they first start their lessons, they find themselves eating raw food in the dark. This is misery too, but the instructors couldn't care less about "character." They're just motivating the students to practice.
This is implied in Harry Potter; growing up with his abusive Aunt and Uncle gave him a lot more humility than his father had at the same age (although his father grew out his Jerk Jock phase eventually).
Appears frequently in stories about British childhoods (especially holidays before mass air travel), such as Emma Kennedy's The Tent, the Bucket and Me about her family's disastrous camping holidays in the '70s.
A recurring theme in Tall Tale America is that people can only get to be heroes if they've got plenty of "rock-ribbed harships" to overcome. Heck, Pecos Bill intentionally makes the cowboy business extraordinarily difficult, just so the cowboys who manage to survive it will be the best there ever was.
In the Quantum Gravity series, devils plant themselves on a victim and whisper these kind of thoughts, keeping the victim in Hellnote read as "separation from God". Demons get...touchy if you confuse demons and devils, as demons believe the exact opposite. Have fun at everything you do, be it painting, singing, fighting, killing, decorating, what have you. A demon with a devil on it isn't even considered a demon anymore, it's an imp.
Crabbit in the Magic Kingdom of Landover series appears to espouse this view. And judging by Mistaya's Character Development while at Libiris, he may be right.
Vergere does this to Jacen BIG time in New Jedi Order's Traitor. This is a fundamental part of Yuuzhan Vong philosophy- the Vong believe that anything worth having or any lesson worth learning can only be purcashed through pain (stemming from their belief that the Creator made the universe by ritually sacrificing his own body). Vergere pciked this up from the Vong, though her definition of "character" turns out to differ rather substantially from theirs.
In Bryan Miranda's The Journey to Atlantis, all of the main characters jointly survive a shipwreck, only to be stranded on a deserted island and have to survive through various other hardships while on said island, forcing them to adapt and grow.
Live Action TV
The series finale of Malcolm in the Middle has Lois sabotage Malcolm's chance at a high paying job because she believes he needs at least a decade more of suffering before he's ready to pursue what (she believes) is his destiny: to become the best President of the United States ever. However, she does have a point under the insanity: Malcolm is a genius and had been accepted to Harvard, where he could learn and excel at anything he set his mind to (which given his IQ and resourcefulness, could be world-changing) if he worked his ass off for it and learned to value hard work and opportunity, rather than waste his potential on working for a pointless corporation that dropped a job in his lap and wanted nothing more from him than what he was capable of in his senior year of high school.
Ace Rimmer from Red Dwarf is this all over. He is different to normal Rimmer because their shared timeline split off when they were children. One of them got held back a year in school, the other didn't. It turns out it's actually Ace that was held back a year, and so he suffered for it (ie by being bullied and suffering the humiliation of it all), and decided to fight back, and continued to fight back ever since, building his character and becoming awesome. Normal Rimmer, on the over hand, was never held back a year, and therefore spent the rest of his life making excuses for himself.
Subverted in the Star Trek: The Next Generation episode "New Ground," when Worf tells his son Alexander that the rigors of Klingon schools are meant to build character — but that their staying together will be an even greater challenge.
A more tragic version in Star Trek: Voyager's "Real Life". The Doctor has created a hologram family to experience a new aspect of humanity. During the course of the episode his daughter suffers a mortal wound in an accident and is dying, so the Doctor suspends the program. Paris points out to him that normal humans don't get to evade the negative aspects of life and persuades the Doctor to see the program to completion and say goodbye to his daughter.
According to Red on That '70s Show, "In order for [my son] to be a responsible adult, he has to be miserable now!"
In Downton Abbey, Cora tries to use this approach to comfort Edith after she's jilted at the altar by Sir Anthony.
Doc Martin: Martin was brought up by emotionally distant and borderline abusive parents who resented having a child at all.
Martin: I was locked in the cupboard under the stairs as a child, and it never did me any harm.
As the trope quote shows, in Calvin and Hobbes, Calvin's dad would often invoke this phrase whenever Calvin (or his mom) complained about their current activity. Bill Watterson stated in the tenth-anniversary book that he took this trait directly from his own father.
Charlie Brown declares that he already has enough character, thank you very much.
In another Lucy assures him, "We learn from our mistakes," and he bellows plaintively, "THAT MAKES ME THE SMARTEST PERSON IN THE WORLD!"
At one point, after Snoopy's doghouse burned down rather tragically, Charlie Brown went to Lucy's booth for some counseling on why these tragedies occurred, to which she gave the rather philosophically pat answer that adversity helps prepare us for what lies ahead in life. For what are we being prepared, then? "More adversity. Five cents, please."
In The Elysium Project, Benjamin Cane, Guardian Entity of the protagonist Emma Grayson, more or less uses this as his reasoning for why he framed her for selling out her friends and getting them all captured by the villains.
Champions adventure Deathstroke. The title villain group decided to make their agents monitor the base's surveillance cameras instead of letting a computer do it because they felt that the boring duty would "build character".
"Money Isn't Everything" from the Rodgers and Hammerstein musical Allegro sarcastically lists the deficiencies of money, concluding that "it cannot build your character or teach you how to starve".
Team Fortress 2 - The Soldier believes this, according to one of his voice clips: "Pain is weakness leaving the body!"
Fire Emblem Awakening - Chrom tells Lissa that "hardship builds character" while she's complaining about having to camp out. She angrily replies that she's "built quite enough character for one day".
Messiah: In the intro, God tells Bob that the upcoming mission will "help build character". "I've got enough character," Bob protests.
MAG ISA — This is the whole point of this comic. Eman, the main hero goes through a lot of misery that the average person would probably end up just killing himself/herself.
In thisUser Friendly strip, Sid claims that obsessive addiction to Nethack is a good thing because it helps build character.
"...[B]ein' a dwarf is about doin' yer duty, even if it makes ye miserable. ESPECIALLY if it makes ye miserable!"
SF Debris takes major issue with this viewpoint in his review of the Voyager episode "Real Life". That episode plays the trope by having a holographic doctor suffer one of the worst real life nightmares and true Adult Fear: hopelessly watching his ill child die. Not surprisingly, the issue never resurfaced for the character in question, which is what earned the episode Chuck's ire.
In Ed Eddn Eddy, after the Eds wrongfully accuse Jonny of being a "serial toucher" and sentence him to rolling down a hill in a giant tire, Eddy justifies it by citing the trope. And given his rather shocking history of abuse from his brother see in The Movie, he might just believe it.
Edd: Should we feel worried about Jonny's predicament? Eddy: Nah! You know what they say, a little childhood trauma builds character.
Zuko: I don't need luck though, I don't want it. I've always had to struggle and fight and that's made me strong. It's made me who I am.
He's just trying to please his Magnificent Bastard father, who claims this is the case, but his philosophy is actually Might Makes Right. His son doesn't agree? Teach him a permanent lesson... On his face.
Ozai: You will learn respect, and suffering will be your teacher.
Zuko: How can you possibly justify a duel with a child?
Ozai: It was to teach you respect!
Zuko: It was cruel! And it was wrong!
Batman is always described as the very essence of this Trope. The loss of his parents made the (probably) most strong-willed person in the DC/DCAU-universe.
In the House of Mouse episode "Goofy For A Day" Max decides to be a waiter to prove to Goofy that waiting is an easy job. When it proves to be tough for Max, Goofy tells him that "goofing up builds character".
Miko of Transformers Prime receives a hefty, and long overdue dose of this during "Hurt". Mostly spending the first one and half season acting as a dipstick, Leeroy Jenkins, who loves getting in the way of missions, "Hurt" brings her down to earth with killing Hardshell, and realizing her buddy Bulkhead will never fully recover from his injuries.
In one episode of American Dad! Stan decided that Steve needed to be bullied for being too passive and Weak Willed and took up the job himself. In response Steve found the guy who tormented his dad in school on Facebook and paid him to beat Stan up. A few seasons later, it turns out Stan's original lesson was right, and Steve not only gets beaten up by said bully, but also the new bully he had been dealing with.
In the season 2 episode of The Simpsons: "Dead Putting Society" Bart and Todd Flanders are neck-and-neck at a miniature golf competition and they have this conversation when they're tied at the final hole:
Bart: This is pretty tense, isn't it, Todd.
Todd: Yeah, my knees are shaking, I got butterflies in my stomach... But I guess this builds character.
Truth in Television in that there are people who subscribe to the philosophy, but sadly, not the desired effect. Bully apologists, for example, use this as an excuse to sit idly by and allow bullying to continue, believing that the abuse will make the victims stronger. The results: not so much. While it is true that people have become stronger in the face of adversity, this does not mean adversity always makes someone stronger.
This does seem to be justifiable Truth in Television when applied to media creators making their characters miserable. Tortured characters seem to sell very well, as long as it doesn't veer into Wangst or Deus Angst Machina.
Plenty of people who've experienced hardship (of any magnitude) value having had the experience because it taught them some sort of useful skill or helped them grow as a person, though they generally agree that they wouldn't want to do it again.
YMMV on whether or not this is actually required to function to an extent. However there is a limit (you may get PTSD for example, which is more a breaking of ones character rather then development of it). The flip-side being is that, since everyone's life always has its hardships, there's really no reason to go piling them on simply for extra misery.
Part of the reasoning behind many ascetic religious/philosophical disciplines and customs that are practiced by many different belief systems - fasting, vows of poverty/silence/chastity, food restrictions (denying oneself meat, alcohol, fatty, sweet, or other "luxury" foods), etc - willingly giving up various indulgences and accepting physical discomfort (even temporarily) is believed by many faiths to strengthen a person's faith and bring them in touch with their spiritual side. It's just believed that pleasurable things get in the way not that hardship itself is necessary. Though several paths do recognise that pleasurable things actually enhance spirituality, if apreciated in a proper way. To a more serious extreme, being persecuted and even martyred for your faith is seen as a badge of honor by many religions.
Part of why countless rites of passages around the world throughout history (especially for guys) involved pain - whether by combat, ritual scarring, piercing, a highly uncomfortable ritual, a dangerous stunt, survival situation, etc - a mere boy cries when he gets hurt, but a real man toughs it out and becomes stronger for it.
Actress Virginia Hey has not been shy about saying that her time on Farscape was incredibly rough on her. Aside from having to shave her head and eyebrows off to play the alien Zhaan, she also had to be slathered in blue body paint that caused her kidney problems during her time on the show (although it should be noted she has no ill will toward the show or its fanbase, and was willing to stay on if they could reach a compromise involving a bald cap and a different makeup, but they couldn't, and she simply couldn't handle the physical toll anymore.) Looking back, she said that she actually enjoyed it for a while, since she felt like, as a former model, she was "paying her dues" and earning her stripes as a full-fledged actor. Other actors (often jokingly, but not always) have similar ideas of having to "pay your dues," involving things like filming scenes in the freezing cold, working with uncomfortable prosthetics, or having to work a long run in theater before truly being able to call yourself an actor.
Friedrich Nietzsche is famous for saying "That which does not kill us makes us stronger". As the philosophy is antithetical to the concept of Inborn Fitness, his belief in this is often used as evidence that he wasn't a Social Darwinist like many who associate him with the Nazis attest.
During most of his public sparring sections heavyweight boxer, Muhammad Ali, would intentionally let bigger men, like Larry Holmes, beat him up in the ring without showing any of his offensive skills. This was so he could master taking punishment and have better defensive reflexes. It paid off during his historical victory against "Big" George Foreman in Zaire Africa, when he laid against the ropes and let Foreman tire himself out by taking punishment.