Renton in Eureka Seven says this a lot, especially as he tried to climb out of his father's shadow early in the series.
Kyou Kara Maou is full of people with subtextual identity issues. The two surviving members of the Half-Human Hybrid Rutenburg division make a study in contrasts on this point:
Yozak is the cheerful, improbably competent, muscled, crossdressing red-headed spy who seems incredibly at home in his own skin, though some of that might be coping mechanism. His mother died and he spent his childhood (i.e. about thirty years) starving because of the customary ostracizing of anyone with half-Mazoku children in Shimaron, and he harbors some resentment against Mazoku for their less virulent but still racist treatment of half-bloods. At any rate, he is very I Am What I Am by this point in his life.
His best friend and captain Conrad, though, is "the perfect guy," probably the best swordsman in the world, of practically royal lineage on both sides but unable to hold any rank higher than 'sir', gives off the creepiest Stepford Smiler vibes sometimes, especially when explaining without rancor about some other shitty thing, and has apparently, his entire life, needed to have someone else to base that entire life around. When he was a kid, he had a Big Brother Instinct around Wolfram. After Wolfram rejected him for being half human, he eventually attached himself to Julia. After Julia died, Shinou arranged for him to transport her soul to Earth and make sure that the baby it became was born safely. And after that, his whole reason for being is Yuuri.
In Midnight Secretary, Kyouhei first considers his vampire pride, where being a vampire is most important thing that defines him. However, later in serie when he is called out by other vampires on how low he has fallen, he claim that it doesn't matter what he does, he is he and that he is vampire no matter what. He also claims that he doesn't want to be bound, but realises that he was bound by his pride as a vampire
Shinji: "I hate myself... But, I might be able to love myself. Maybe my life could have a greater value. Yes, I am nothing but I. I am I. I wish to be me. I want to continue existing in this world! I am worth living here!"
Inori in Guilty Crown accepts that as long as she can protect Shu, she doesn't care if she was just created to be the host for Mana's soul.
Kabuto of Naruto came to believe that his existence was a lie and so he reshaped himself into a different person to escape that lie. Itachi trapped him in an Epiphanic Prison which Kabuto only escaped when he accepted his original life.
Too many characters to count among Marvel Comics X-titles and mutant spin-offs. Whether hero or villain, whether their ability has inconvenient side or not, whether angsty over it or taking it in stride, before, during or after an about-face (or about-heel) and back, almost every one has an I Am What I Am moment at some time.
Balto: Balto spends the first half of the movie angsting over his half-wolf heritage, but then buckles down and uses his ?wolf powers? to save the sled team and get the medicine to town.
Dumbo: Dumbo is teased for having abnormally big ears, which are what later enable him to fly. As his friend Timothy Mouse puts it, "The very things that kept you down are gonna carry you up and up and up!"
This is perhaps the main moral behind The Nightmare Before Christmas. Jack Skelington, the Pumpkin King, had become bored and dreary with scaring and longed for something more. After discovering Christmas and attempting to take a shot at it, only to fail miserably, he has a BSOD Song which leads to up to this trope:
Well, what the heck! I went and did my best! And by god, I really tasted something swell! And for a moment, why, I even touched the sky! And at least I left some stories they can tell, I did! And for the first time since I don't remember when, I felt just like my old boney self again! And I, Jack, the Pumpkin King...That's right. IAMTHE PUMPKIN KING! HA! HA! HA! HA!
Wreck-It Ralph has the Bad-Anon Creed: "I am bad, and that's good. I will never be good, and that's not bad. There's no one I'd rather be than me."
Repeated at the end, it becomes a combination Tearjerker and Crowning Moment of Heartwarming when it's implied he feels proud of being a hero in Vanellope's eyes, even if the rest of the world views him as a villain.
Film - Live Action
One of Max's last actions in the movie Bent is taking off his shirt and replacing it with a blood stained shirt with a pink triangle sewn onto it, to finally show pride in himself against the nazis.
That's the main motive behind A Better Tomorrow. Initially, Mark is convinced that gangsters like him can't really change their ways and run an honest life, and at one point even scolds about it his former boss Ho, who is trying to do just that. But later on, Mark acknowledges the fact that only by taking their destinies straight in their hands, people can really call themselves free, and even ends up being killed while lecturing Ho's brother (who is a cop and quite the Inspector Javert of the situation) on the goodness of Ho's efforts.
An unusual villanous example in Kingdom of Heaven: the Templar Grand Master stands dripping blood from men, women and children and stares into the middle distance - "I am what I am... somebody has to be."
Del: You wanna hurt me? Go right ahead if it makes you feel any better. I'm an easy target. Yeah, you're right, I talk too much. I also listen too much. I could be a cold-hearted cynic like you... but I don't like to hurt people's feelings. Well, you think what you want about me; I'm not changing. I like... I like me. My wife likes me. My customers like me. 'Cause I'm the real article. What you see is what you get.
Note Del's very brief hesitation before saying "My wife likes me;" it's a beautifully subtle touch from actor John Candy as well as some rather tragic foreshadowing to the reveal that his wife actually passed away years ago.
Frederick in Young Frankenstein, after confronting his creation, he tells him how wonderful he is and promises to show that to the entire world, embracing his heritage at last.
In an episode of Red Dwarf, Kryten the android becomes human. At first he's thrilled, because mechanoids tend to view humans as awesome. As he starts belittling his origins and insulting his spare heads, he starts to realize that he can't change what he is inside; an android who can't tell the difference between Popeye and Descartes. Also, it provides this funny moment:
Human Kryten (Hands Lister a Poloroid photograph of his penis): Is that normal?
Lister: What, taking pictures of it and showing it to your mates? No, it's not."
Parodied in The Catherine Tate Show. Jamie, fed up with his grandmother constantly criticising and swearing at people, says in despair "Why are you like this?" She responds by launching into a rendition of "I Am What I Am" from La Cage aux Folles.
Spock throughout Star Trek. He even addresses it word-for-word in "This Side of Paradise":
Spock: I am what I am, Leila, and if there are self-made purgatories, then we all have to live in them. Mine can be no worse than someone else's.
One episode of Pushing Daisies has Ned say that he's not sorry or ashamed about what he does, because "it's what brought everyone I love into my life".
Kurt from Glee: He decides he's not afraid to be who he is, and tells his father that he's proud to be who he is, and that he won't hide in the closet.
In episode seven of Game of Thrones, the Magnificent Bastard Petyr Baelish describes to a couple of his "employees" the epiphany he had in regards to this trope after getting defeated in a duel, saying, "I learned that I'll never win, not that way. That's their game. Their rules. I'm not going to fight them. I'm going to fuck them. That is what I know. That's what I am." Rather than try to be a warrior, he vows to be The Chessmaster.
In the season 3 premiere of Breaking Bad, Jesse, blaming himself for the death of Jane and the airplane crash that her distracted father accidentally caused, tells Walter, "It's all about accepting who you really are. I accept who I am. I'm the bad guy."
Veronica Mars: Invoked word for word in response to people sometimes calling her out on her role in upheaving people's lives (she's a private investigator - and naturally nosey).
Lake Wobegon's town motto, according to Garrison Keillor, is the plural form of this: "Sumus quod sumus, we are what we are"
Jane Eyre: Jane decides that, if she has to live without friends and without love to keep her self-respect, she will do so. That is her nature, not to compromise, and she will be true to it: "the more friendless, the more unsustained I am, the more I will respect myself."
This phrase and variants of it are repeated throughout the first book of the Sword of Truth series, usually after one character or another laments that they wish they were someone else, who didn't have to worry about their magic or saving the world..
Don John, the villain of Much Ado About Nothing makes an introductory speech in which he tells his henchmen that he's being a Jerkass because he is, in fact, a Jerkass and has decided not to fight what he is.
Richard III: "Since I cannot prove a lover, I am determined to prove a villain".
Discworld: In The Wee Free Men, Tiffany Aching overcomes the Fairy Queen with the very selfishness the Queen taunted her for when she realizes she's willing to fight for the things that are hers. Then she lays claim to the entire land.
Galaeron Nihmedu. First, he suffers from prejudices as a sorcerer, then he's cut off the Weave (one of worst fates for an elf) and others see him almost as undead. But once he regains control over himself, he does what's right for him and neither reacts to cold reception nor wangsts himself out.
This is a dominant theme of The Speed Of Dark by Elizabeth Moon, which is told from the viewpoint of an autistic character. That said, given the choice in the end of whether to undergo surgery that will cure them, not all of them will end up choosing alike.
Some of the characters from The Mortal Instruments Trilogy by Cassanda Clare; the obvious one being Alec being gay. Also maybe Jace and Clary with their father.
The Bible: In The Book of Exodus, God famously responds to Moses asking Him for His name with something we can't quite translate into English - it's often rendered as "I AM WHAT I AM" or "I WILL BE WHAT I WILL BE". In doing so his God proclaims that He is beyond mere names and references the Hebrews' (sacred) placeholder-name for their technically-nameless God, YHWH (lit. "that which was, is, and will be"). Another translation of the line (quoted in Dogma) is "I AM HE WHO IS CALLED 'I AM'."
This can also be interpreted as God saying that as He's the only one, he doesn't need a specific name. If there was only one tree in the entire universe, we'd just call it "the tree", not a fig tree or a birch tree or anything of the sort.
From the same Source is an arguable contender for the Trope Namer. Paul, while addressing the Church of Corinth, explains the simple origins of faith and the ideas around which the Gospel is shaped. He describes the humble salvation of the twelve disciples and then his own, giving us this piece:
In one fantasy short story, God tells the modern world (by having every single broadcast radio and TV signal at the same time announce it) to justify humanity's continued existence within a short deadline. After the U.S. government puts in every known fact into a computer, the computer gives them the name of someone to talk to. When they talk to him, he thinks for a few minutes and replies with the (slightly adjusted) Bible quote above. "We are what we are".
The following exchange from Night Watch between the Light Other Anton and the the Dark One Zavulon:
Anton: "Zavulon, you are the spawn of darkness."
Zavulon: "Indeed, I am. But only that darkness that was inside me."
In V. Gor's Demon series of novels, a human brain copes with the dogfighting in space all right, the problem is the body housing said brain. A few planets start searching for volunteers to undergo augmentation.
The eponymous Demons are said volunteers for whom the Bio-Augmentation worked properly, including a few who were successfully treated for the various Psycho Serum side effects.
The Devils are former rejects from the Demon project. The project was considered a mixed blessing at best as a significant number of volunteers became SuperSoldiers without the desired piloting skills. They became the dedicated ground force for the war to free the far more valuable pilots from planetside action.
The Ares project claimed to replace human pilots with a superior AI. Since no known AI can handle space combat, the unscrupulous scientists simply took both volunteers and rejects from society and encased their brains on life support in the ships. \ Demons and Devils are fertile, but only among themselves, effectively becoming new humanoid species. All three groups, Demons, Devils, and Ares fighters, slowly come to realize and accept that their aren't human anymore. Avoiding both Pro-Human Transhuman and Transhuman Treachery, they pledge their loyalty to the Demons' native planets only.
Eminem: "I am whatever you say I am! If I wasn't, then why would I SAY I am?! In the paper, the news EVERYDAY I am! I don't know, that's just the way I am."
The song "What I Am" by Edie Brickell and the New Bohemians ("What I am, is what I am, is what you are or what"); referenced in the Aretha Franklin song "A Rose is Still a Rose"
"I'm Real" by Jennifer Lopez (both the original, and the remix with Ja Rule).
Meredith Brooks' song "Bitch" is all about this trope; the chorus proudly proclaims "I'm a bitch, I'm a lover," followed by several other contradictory attributes (Child/mother, sinner/saint) and announces "I do not feel ashamed!".
Mercy Me's "No More, No Less."
This is said by the narrator in the Alice Cooper song Fantasy Man
Lady Gaga's single "Born This Way" (2011) from her second studio album of the same name.
Don't hide yourself in regret Just love yourself and you're set I'm on the right track, baby I was born this way — Born This Way, Lady Gaga
The Imagine Dragons example at the top of this page is arguably about this theme. It's about embracing who you really are and how it's impossible to do so, even when minor changes in your life are made.
La Cage aux folles: In the Act I finale, Albin, a professional drag queen, has learned his longtime partner and their adoptive son want him out of the way to avoid offending the son's conservative future in-laws. He sings the eponymous song in defiance, declaring that he, at least, is not ashamed of who he is.
Elphaba, in Wicked, sings 'Defying Gravity' as a realization of her own nature and her own standing in the world: she will never gain the love she's dreamed of and still be able to respect herself. She's hated being a witch, and she's tried not to be a witch, but it's her nature, and for the first time she really embraces it.
Monsieur Madeleine, in Les Misérables, comes to accept who he was before and trusts in divine providence to come to the bar and say, "Who am I? I'm Jean Valjean!"
Nancy is fully aware of the fact that Bill is a complete bastard, but she can't help loving him, complete with song. And then, to top off the love fest, he kills her.
West Side Story: "I love him, I'm his, and everything he is I am too - I have a love, and it's all that I need, right or wrong - and he needs me too."
Funny Girl: In a vein combining 'I Have a Love' with 'Defying Gravity' above, 'Don't Rain On My Parade' is Fanny Brice telling the rest of the Ziegfield follies, and Ziegfield himself, to go jump in a lake, because she knows what she wants and she's not going to let him get away.
"I, Don Quixote" says it right in the title: "I am I, Don Quixote! the Lord of La Mancha..."
His "fair lady Dulcinea" spits out the darkest possible version of an I Am What I Am song, saying that she is what she is: an unloved, unremembered whore who comes from a dog-eat-dog world and that's only way she can be, and all she deserves.
When Iago of Shakespeare's Othello says "I am not what I am" in a soliloquy, he means a couple of things. Firstly he's telling us he's a manipulative bastard, and possibly a psychopath rather than the honest and reliable man the other characters think he is. Secondly, this statement also roughly equates to him saying that he is soulless and therefore daemonic. Iago is fine with this and he's quite happy admitting his true colours to himself and to us as the audience.
Shrek The Musical: Near the end of the show, during the titular character's 10-Minute Retirement, the various fairy tale characters exiled from the kingdom band together via the song "Freak Flag", wherein they embrace what makes them different from "normal" people, and decide to fight back against Farquaad themselves.
Oscar: You mean you're not going to make any effort to change? This is the person you're going to be—until the day you die? Felix: We are what we are.
In the 2013 stage adaptation of Charlie and the Chocolate Factory, Willy Wonka has the song "Simply Second Nature", in which he explains that his strange confectionery creations are born of a desire to create beautiful things; he cannot help but follow his muse, he happens to use sweets as his artistic medium, and he doesn't care if others find him strange for it.
Kingdom Hearts Chain of Memories: Riku spends most of his side the work trying to fight his darkness. When he finally decides to use it to save himself, he's actually called out on it by one of the antagonists - and responds with a reworded version of this trope:
Zexion: Heh... After all your protests you're still just another darkling.
Riku: I know who I am.
Every party member in Persona 4 does this to obtain their Persona.
In the canon route of Blaze Union, Garlot has it dropped on him quite abruptly that he's not who he thinks he is—as much as his mother tried to hide it from him, he's actually a pureblooded descendant of the demon Brongaa, and his real name is Gulcasa. As this comes in the middle of a brutal Trauma Conga Line, it would probably be forgivable for the poor kid to break down from the identity crisis... but he just accepts the truth calmly and then sets about trying to find a way to use his newfound power to protect people. At the very end of the game, he puts the spirit of this trope into words, but by then it really comes off as more of a Tear Jerker than anything else, as several people who meant a lot to him have utterly rejected him because of this.
In Sonic Adventure 2, Sonic gives one in response to Shadow's inquiry of what special kind of creature Sonic must be to have been able to conduct Chaos Control (especially notable as he did it with a fake Emerald, something Shadow views as impossible) and escape certain death from that explosion. Sonic's answer is the defining moment of his character: "What you see is what you get: just a guy that loves adventure. I'm Sonic the Hedgehog!"
In Shadow the Hedgehog, at the end of several story routes and especially the final, canon route Shadow states, "This is who I am!" when he is finally at peace with his (perceived) identity and has put the past behind him once and for all. Shadow comes to terms with the idea that he is a weapon designed by Gerald Robotnik, but he has decided that he can be so much more than just a weapon: with his powers, he will find a way to bring the people of the Earth happiness, just as Maria had hoped.
Metal Gear Solid series: One of the constant struggles for Solid Snake's character is that he has Blood Knight tendencies. Snake's father Big Boss and his brother Liquid remind him that inside of him there is a warrior spirit that loves to fight and that he should embrace it, and revel in the joys of battle. After a long internal struggle Snake does eventually come to terms with his love for violence and embraces his fighting nature, but tries his best to separate himself from the examples of his family by using his combat talents for good causes. As an outward sign of his internal struggle Snake gives non-lethal combat a chance in Metal Gear Solid 2, but eventually falls back into using lethal weaponry on the battlefield. Despite his attempts to do good Snake eventually despairs in the knowledge that he can't escape his violent nature and admits that he is a bad person at heart with an irredeemable killer nature. Snake actively protests the idealistic images people have of him being a hero simply because he stopped a few terrorist incidents, stating "I am no hero, never was. I am just an old killer."
In the end of his optional introspection storyline in Assassin's Creed: Revelations, Desmond arrives to the realization: "My name is Desmond Miles. I am an Assassin. I am an Assassin." Notably, he has denied being an Assassin multiple times since game one.
In Worm, Taylor, after failing to prevent the end of the world, admits to herself that she is a hypocrite, selfish, and occasionally short-sighted in spite of her attempts to be better, coming to terms with these parts of herself.
I’m just a little bit of a monster.
Mean-spiritedly subverted in Demo Reel. After four episodes and God knows how many years of self-loathing, Donnie DuPre accepts himself as both Donnie and Jimmy Boyd, a film-maker who will make good movies and someone who can remember his tragic past but not obsess over it anymore. Turns out he's neither, he's The Nostalgia Critic, and his whole existence is a punishment.
Popeye: "I yam whats I yam, and dats all dat I yam"
Avatar: The Last Airbender: "My name is Zuko, son of Ursa and Firelord Ozai, Prince of the Fire Nation and heir to the throne.". This doubles as a Badass Boast, although while it intimidates his opponent, the people he was protecting from them really don't like who he is and run him out of town.
In the first episode of Gargoyles, Goliath responds to humans' dislike of his race with "We are what we are".
Justice League Unlimited episode "The Doomsday Sanction" features a villainous example. When Doomsday says that he'll kill Superman, he asks why. The creature replies "It's what I am. I don't care why."