The titular Ben Tennyson gets this in the very first episode: Before the opening theme song, he's shown bored out of his mind, making a paper airplane that he then throws at his teacher, copping a delighted look on his face. After the theme, he is seen rushing to the aid of a terrified kid who's being picked on by two bullies. Though he fails, he refuses to budge. That shows that, while he still has immature tendencies, being ten years old and all, he is willing to stand up to any evildoer, knowing full well that there is a high percentage that he can lose the fight.
In Ben 10: Omniverse, Rook's first scene in a fight utilizes him showing what his Prototool can do, and taking out three alien criminals singlehandedly... But when in conversation with Ben, showcases a misunderstanding of sarcasm and literal mindedness.
In South Park, both of Kyle's parents have these. The first thing Sheila Broflovski does in the show? Try to cancel Terrance and Phillip by going on strike with all of the other parents. 4 episodes later, Gerald is being too hard on Kyle this Hanukkah for having what was thought to be an imaginary friend. They both mellow out a little as the series progresses, for the most part.
Woody Woodpecker established his heckler nature by bursting onto the screen, saying a smug "Guess Who", dodging a subsequent blow from Poppa Panda, retorts by honking his nose like a horn, and then unleashes his legendary laughter as he treks off to reek havoc on the Panda's rooftop. His second (albeit first solo) appearance in "The Cracked Nut", where he sings a Bragging Theme Tune about how he's crazy and he's proud of it, is another one of these moments.
Iroh as well. He just wants to finish his game and drink some tea.
Ozai's first talking-and-doing-things appearance (as opposed to the brief silhouette he got a few episodes earlier) features him burning Zuko's face. His own son. In public. As the 13 year old boy begs for mercy. That's all we need to know about the guy.
Azula's first appearance during Zuko's flashback in "The Storm". All you can guess about her is that she's family by the fact that she's standing next to Iroh, has yellow eyes, and is dressed in very similar robes, but when she's seen smiling as Zuko gets disfigured, you know she's going to be trouble whenever she'll show up. When she shows up as a named character it is one of these. We can tell from her first appearance that she is a vicious creature, and that is the truth all the way through the series. We also get a more subtle hint of her vanity when she blows a loose strand of hair out of her face with a peeved look, which only makes her Villainous Breakdown much later all the more epic.
Azula: Do the tides command this ship? Captain: Uh, I'm afraid I don't understand. Azula: You said the tides would not allow us to bring this ship in. Do the tides command this ship? Captain: No, Princess. Azula: And if I were to have you thrown overboard, would the tides think twice about smashing you against the rocky shore? Captain: No, Princess. Azula: Well then, maybe you should worry less about the tides, who have already made up their minds about killing you, and worry more about me, who's still mulling it over.
Toph's entrance, which consists of her effortlessly beating a man about five times her size in the Earth Rumble ring without breaking a sweat also qualifies her as a Little Miss Badass. Did we mention that she's also blind?
When Tenzins entire family is introduce we get a good description of each of their personalities Ikki was introduced as asking "Are We There Yet?" ad nauseum, while her little brother Meelo chews his father's head.
Asami crashes into Mako on the street. A couple minutes later, she takes him out to dinner, and gets her father to fund his team to make up for it.
In the Season 1 finale, we are introduced to Tenzin's older brother Bumi. His only action in the ten seconds of screen time he has is to let out a huge WAHOOO! before grinning like a maniac.
In Season 2, Mako's first appearance is him, now a cop, stopping out a van full of criminals by knocking them over. Then he suggests that they should call the police for help. Given his dour disposition throughout the first season, this marks a big change. He later shows Korra he actually wrote potential one-liners ahead of time.
Terry McGinnis' first scene in had him defending monorail passengers from a Jokerz gang member harassing them. Later scenes showed him with a bad attitude and temper, but established his character arc for the first few episodes.
Mad Stan in is introduced shouting "BLOW IT ALL UP!" into the camera and sticking a bomb onto a support pillar while heavy metal music plays in the background. Guessing he's a Bomb Throwing Anarchist isn't exactly difficult.
Ron Stoppable's first moments establish him as the Goofy Best Friend:
Kim: A naked mole rat? Ron, ever think about getting a normal pet? Ron: Like what? Kim: Something not naked. (Rufus blows a raspberry at Kim) Ron: (dramatically) Never be normal, that's the Ron Stoppable motto!
Darkwing Duck's very first scene in his premiere episode perfectly illustrates that "ego the size of a small planet" Taurus Bulba will later summarize. It leaves no doubt what this protagonist's personality is like.
Ruby Gloom's first episode gives introductory scenes to most of the cast. The best one may be Misery's, where a few sentences into an already gloomy conversation, she puts the always-optimistic Ruby at a temporary loss for words by describing her own genetic predisposition toward being struck by lightning.
Two seconds later, Ruby further establishes her own character by changing the subject and managing to lift her spirits a little anyway.
General Grievous' first appearance in Star Wars canon is the season one finale of Star Wars: Clone Wars, where he takes on a team of six Jedi, and kills or incapacitates all but one of them.
Unfortunately, while Grievous' reputation as a dangerous foe carried over into Revenge of the Sith, all of his screen time is spent running away or getting his butt handed to him by Obi-Wan. So in the Expanded Universe, Grievous is quickly established as a legitimate threat, but in the movie it just comes across as an Informed Ability.
In the movie, he first appears as a skull-faced boss villain, and the first thing he does is coughing uncontrollably. Thus: He is sick (In fact he suffers from Incurable Cough of Death), and he cannot be a robot because he is sick (Cybernetics Eat Your Soul, someone?), so there must be something organic somewhere to Dragon His Fett. An Establishing Character Moment saying he's a pitiful, or by now at least pitiable, villain.
The shift in characterization is a result of the constantly shifting production of Episode III. While initially he was supposed to be a powerful and feared Jedi hunter, Lucas decided to rewrite the character as a moustache-twirling coward. The in-story reason is that towards the end of the Clone Wars cartoon, MaceWindu Force-Crushes his chest — and with it, his few remaining organs, leaving Grievous horribly weakened during the events of Episode III. As for Grievous vs. Kenobi? Obi-Wan is considered the master (not a master, the master) of the ultimate defensive lightsaber form, and thus could block all Grievous' attacks 'cause he's so damn good at blocking attacks. And when Grievous kept failing to hit him, he got angry, which made him get sloppy, which made him get angrier, which made him get sloppier, and... you get it.
Very true. A deleted scene gives him a very different ECM... with him executing Shaak Ti. Being a deleted scene this was retconned and her death was saved for a much later Crowning Moment of Awesome for Vader's Apprentice.
Family Guy's Glenn Quagmire and his dealings with a woman he picked up earlier that night:
Woman: Hey, Glenn, I have a question for you: what do you do for a living? Quagmire: [wearing a lecherous grin] And I have a question for you: why are you still here?
The first episode of Total Drama Island was full of this. Some memorable ones were Owen's excitement, Cody's Casanova Wannabe entrance, Leshawna starting a fight with Harold, and Tyler and Bridgette's Dojikko behavior. Courtney's adherence to rules and order, strategic Alpha Bitch status were also partly revealed in the second episode.
Dinobot enters Beast Wars by defecting from the Predacons and challenging the Maximals' leader, Optimus Primal, to a duel to the death for leadership. Up to now, he's been portrayed as a back-stabbing villain, fully subscribing to his race's tradition of treachery and dishonor. Then, when Optimus Primal slips and nearly falls off the narrow bridge they're fighting on, Dinobot helps him up, revealing himself to be a decent, honorable guy, for all that it's worth. This quote illustrates it:
Optimus Primal: What're you doing? You'd won! Dinobot: You slipped. To defeat you in such a manner would be lacking in honor. I would not have earned the right to lead. I prefer to defeat my opponents the old fashioned way — BRUTALLY!
Icy Blitzwing: As usual Blackarachnia: your demeanor is as unpleasant as zat accursed organic mode of yours. Blackarachnia: Blow it out your actuator, three-face. Hothead Blitzwing: Ze name is Blitzwing, insect! Remember it! Cause it's the last thing you will hear before I- Random Blitzwing: -express my feelings in song! Ze itsy bitsy spider...
Showing that Transformers loves this trope, Prime has Knock Out and Breakdown, AKA Those Two Bad Guys, showcasing the former's vanity and the latter's bruiser status, and then they manage to work in tandem to overpower Optimus and the rest of the Autobots, showing that they aren't normal Vehicon mooks.
The first thing Cliffjumper does in Prime is boast about freaking out some cops. The second thing he does is jump into a fight alone with several Vehicons. The third thing he does is die.
In the first full-length Simpsons episode ever broadcast, "Simpsons Roasting on an Open Fire", Lisa's intelligence and precociousness are demonstrated by her eloquently telling off her Aunt Patty for badmouthing Homer.
Lisa: What, Aunt Patty? Patty: Oh, nothing, dear. I'm just trashing your father. Lisa: Well, I wish you wouldn't because, aside from the fact that he has the same frailties as all human beings, he's the only father I have. Therefore, he is my model of manhood, and my estimation of him will govern the prospects of my adult relationships. So I hope you bear in mind that any knock at him is a knock at me, and I am far too young to defend myself against such onslaughts. Patty: Mm hm. Go watch your cartoon show, dear.
My Little Pony: Friendship Is Magic: When we first meet Twilight in "Friendship is Magic Pt 1", she's studying with her friend/assistant Spike, who's trying to get her to relax, and is shown to be uninterested in making friends and a bit insensitive at times. After being sent to Ponyville, she meets the rest of the main cast through a series of these. Pinkie Pie jumps in the air while gasping dramatically and promptly runs away, with no explanation given for her bizarre actions. Applejack greets Twilight over-enthusiastically before inviting her to brunch with her large family. Rainbow Dash crashes into Twilight and sends her into a mud puddle, tries (and fails) to clean her up with a speed-based stunt, openly laughs at Twilight's resulting messed up hair, proudly declares her ambition to join an elite aerial team, and clears the sky in ten seconds flat. Rarity is decorating for the Summer Sun festival, gives Twilight a makeover, and starts gushing over the glamour of Canterlot on learning that's where Twilight is from. Fluttershy is working with small animals and is painfully shy. And Pinkie Pie wasn't scared of Twilight; she just left to throw her a party. Yes, the second they met.
In "Luna Eclipsed", we finally get to see how Princess Luna normally acts. The answer? VERY LOUD! Immediately followed by complete confusion at everypony's terrified reactions, and her storming off with a huffy "Very well, then! Be that way!"
In "Return of Harmony Part 1", Discord first appears in the stained glass windows, demonstrating a sense of mystery and even humour through his antics amongst the window displays, as well as great knowledge of the Mane Six that by all rights he shouldn't have, what with being sealed in stone for over a millennium now.
Discord: Make sense? Oh, what fun is there in making sense?
Similarly, on that show, Iron Man first appears in "Breakout" (following some scenes in promotional shorts and a compilation of those shorts) as he effortlessly breaks up a weapons sale, tells off Doctor Doom's representative, blows off Nick Fury and SHIELD, and dismisses a request that soon comes back to massively bite him (and everyone else) in the ass.
If you do count the shorts and their compilations, Iron Man's establishing moments come when he fights a giant robot and shrugs off advice that he'd be better off making weapons than fighting evil directly and alone.
The Wasp's establishing moment comes in the short "Enter the Whirlwind" (also featured in the show's fifth chronological episode). She tells Ant-Man that the two of them need to find a better use of their time than private scientific research, then goes outside to fight Whirlwind. Ant-Man eventually comes to help Wasp, so she tells him they could use their powers to benefit others through crimefighting.
With Black Widow at his side, Hawkeye makes his debut in "Hulk vs. The World" by striking the Hulk with two arrows, descending from a plane on a zip line, and quipping, "Tick tick boom!" right before the arrows explode.
Looking back at the first episode, it's hilarious how straightforward this was. As the first scene was a practice session, we were treated to, in order, Donatello and Michelangelo being berated for their failed attempts to put out a candle with some amount of fondness from Splinter, "Poor choice, Raphael", and Leonardo succeeding where his brothers failed. That sums up the series, with, perhaps, more jokes and Techno Babble from Mike and Don, respectively.
There's also the first verbal exchange between Raphael and Leonardo, right after the training session:
"We know that this guy is a crime-fighter who probably doesn't have any super-powers. At the very least, he can't run faster than a car and if you punch him, he'll feel it. We know that he doesn't use guns, and instead relies on being an incredible fighter who uses other means to deal with his enemies. We know that he's violent, and that he hates crooks, but he doesn't kill them and instead hands them over to the justice system. We know he exists because there's unchecked crime in this city that the police just cannot fight by themselves, even if through extraordinary means. Also, he drives a dope car."
Clara, upon meeting Foxxy for the first time, assumes she's a servant and asks her to fetch her bags, which Foxxy does not take well.
Captain Hero's desire for Anything That Moves is indicated when he confesses that he'd "stick and stir any one of those broads," but wants a "hot black chick," too. When that is granted, he waits, in vain, for a twelve year old and a donkey to come.
The first appearance Dr. Rockzo The Rock n' Roll Clown on Metalocalypse. Try to guess what he does He does cocaine.:
Oooh ka-ka-ka-ka-ka-ka co-ka-ka-ka-yeeeaaaaah! I'm Dr. Rockzo the Rock n'Roll Clown! I do cocaine! I hear it's somebody's biiiiiirrrrrrthdayyyy! I do cocaine! Dr. Roczo's gonna make you a balloon bass! (Seriously, dude, a lot of cocaine).
In Thundercats 2011 young Catfolk Prince Lion-O is introduced sneaking cloaked and hooded into the worst part of Thundera's slums, only to catch the eye of a gang of "Alley Cat" muggers who've just finished beating a hapless Dog. He manages to fight most off but has to be bailed out by Action Girl Cheetara, to whom he reveals his reasons for being there: to find rare and obscure pieces of "technology," which everyone else believes to be a myth.iron
In his second appearance in the DCAU, Darkseid establishes exactly who he is to Superman on their first meeting. Superman demands to know who he is and Darkseid just stands there, not saying a thing. After a little pushing, Darkseid uses his Omega Beams to torture Superman and forces him to bow down and finally responds with "THAT is who I am." And thus the relationship between arguably the two most hated enemies in the entire DCAU was established.
In the first episode of The Hub's Pound Puppies, each member of the Five Dog Band gets one: Yipper meets Lucky, the likable and quick-thinking leader; Cookie, the tough-but-motherly second-in-command; Niblet, the big dumb lovable oaf; Squirt, the fast-talking streetwise guy; and Strudel, the book-smart and temperamental inventor gal.
The Looney Tunes Show: Bug's and Lola's first date in "Members Only" shows everything you need to know about Lola in less than ten minutes.