The first scene of the pilot episode, where Jack races through the chaotic wreckage of Oceanic 815, saving one life after another in full-doctor mode as there is screaming and explosions happening all around. Afterward, when he goes off by himself, we discover he sustained a nasty gash to his lower back when he landed in the jungle. Not only that, but he's also clearly dealing with some personal issues. And he still was able to do all that. It's truly an Establishing Character Moment for Jack.
First episode: We don't know who Kate is. All we know is that she is scared to the point of tears of the whatever-it-is that tore the pilot out of the plane, and she does not want to go back although she knows she should. She counts to five. And then she stops hiding, interrogates Charlie, and goes back for Jack.
Sawyer's first moment of badassery. Something loud and feral is running towards the group...and they all flee, while he stands calmly, reveals a pistol from his person, and shoots what turns out to be a polar bear. His comments afterwards push this into Funny Moment too. "I JUST SHOT A BEAR!"
The Reveal that Locke was in a wheelchair before the plane crash in "Walkabout." "Don't tell me what I can't do", indeed. His smirk at the very end of the episode as he watches the wheelchair burn is one of the most badass smiles of the history of television. ◊
Jack gives a No-Holds-Barred Beatdown to Ethan Rom. Especially cathartic in that the last time they saw each other, Ethan beat the shit out of Jack.
Charlie shooting Ethan in heavy rain, without much time to aim and getting him in the chest four out of six times, despite a complete lack of any real training with guns. A very satisfying Karmic Death after he kidnapped Claire, hanged Charlie, killed Scott (of "Scott and Steve" fame) and generally terrorized the Losties for several episodes in a row.
When Kate is grabbing supplies to try to save Boone's life, she just bluntly says what she needs and Sawyer immediately gives her everything she asked for without so much a witty quip.
The raft finally launching in "Exodus, Part 1".
Locke blows up the hatch after almost a season's worth of buildup.
Sawyer removes a bullet from his shoulder with his bare hands.
Mr. Eko killing the Others that came to take him away on the first night after the crash in "The Other 48 Days".
Sawyer's long con in order to take possession of the guns.
Jack utterly destroying Sawyer (a professional hustler) in hand after hand of poker. In exasperation, Sawyer (who had recently conned the group out of their only cache of firearms) proposes one last hand and allows Jack to name the stakes. Jack decides to play for the medical supplies Sawyer was hoarding. After winning the hand (going all in with a pair of nines), Jack tells Sawyer he'll come around later for the meds. Sawyer asks why they didn't play for the guns, as Jack was trying to build an army at the time. Jack scoffs and says "When I need the guns...I'll get the guns."
Hurley's beatdown of Sawyer after one too many fat jokes.
The moment in which Michael Emerson went from guest star to full-fledged cast member:
"Henry":(eating cereal) Course if I was one of them - these people that you seem to think are your enemies - what would I do? Well, there'd be no balloon. So I'd draw a map to a real secluded place, like a cave or some underbrush, good place for a trap. An ambush. And when your friends got there, a bunch of my people would be waiting for 'em. Then they'd use them to trade for me. [jokingly] I guess it's a good thing I'm not one of them, huh? (Beat) You guys got any milk? (LOST end screen)
Sayid is convinced Henry Gale is not who he says he is. Everyone think his grief over Shannon has clouded his judgment but he is ultimately proven right.
Rose: Jack, if you say "Live Together, Die Alone", I'm going to punch you in the face.
Juliet, in her very first episode, goes from baking muffins and hosting book club to knocking Jack out with a single punch.
After Ben manipulates Jack into performing surgery on him, Jack suddenly takes charge in the middle of the operation, knocking out the henchman next to him and holding Ben's life for ransom so that Kate and Sawyer can escape.
Although because of Kate's urgings he did eventually perform the surgery, Jack was pretty darn awesome after he first figured out Ben's scheme before Ben had intended and then shot him down gloriously. He asked a lot of questions seeming to indicate he planned to do it, and when Ben gets all happy and 'we'll get whatever you need to do it' he just laughs and says 'Oh, I was never going to do it. I just wanted you to know how you're gonna die'.
In a flashback, Mr. Eko kills three gun wielding drug lords with a machete while dressed as a priest. With his hands tied.
Juliet gives Danny Pickett three rounds to the chest without blinking an eye to help Kate and Sawyer escape.
Jin chasing down and beating the crap out of Mikhail.
Locke apologizes to Jack, and a submarine explodes behind him.
"Well, I'd say I hope it's big enough to imagine yourself up a new submarine."
Sawyer killing Anthony Cooper (Locke's father/the man who caused Sawyer's father to kill his mother and himself). Especially the way he inhumanly snarls "You wanna go to hell!?" while delivering the coup de grace.
"Well, ain't that something. Sawyer's my name, too."
Charlie saving a woman, who unbeknown to him is Sayid's lost love Nadia, from a mugger in an alley in a flashback in "Greatest Hits". Nadia tells him three people walked past the alley and did nothing, and Charlie was obviously wary but did it anyway.
Nadia: You are a hero, sir, and don't let anyone ever tell you differently.
Desmond: You've got five seconds to talk, brother!
Mikhail: That's a flare gun.
Desmond: And how do you think it'll feel, taking a flare gun to the chest at this range?
Jin takes out two Others by shooting them directly, after his dynamite fails to detonate. Then when he's captured and the Others seem seconds away from executing him, his response (in Korean)? "Go to hell."
Tired of being told he'll "just get in the way", Hurley charges down a group of Others with a Dharma van, providing a distraction for Sayid's moment of awesome: snapping a bad guy's neck, with his feet, while tied up, on his knees, on sand.
Sawyer killing Tom "for taking the kid off the raft."
"Something Nice Back Home", while ostensibly a Jack-centric episode, is one continuous Episode of Awesome for Juliet Burke. With Jack incapacitated by his appendix and in desperate need of surgery, Juliet immediately steps into a leadership position and organizes the survivors to acquire medical supplies and create a safe operating environment... on the beach. Even though Jack shows that he doesn't trust her to perform the surgery, insisting on only local anesthetic and Kate holding up a mirror so that he can direct the surgery, Juliet has him knocked out with chloroform and ejects Kate, and completes the surgery. Then, having realized that Jack has feelings for Kate, she gracefully bows out of any "race" for Jack's affections, because damn it, she's not going to get trapped in any interminable Love Triangle if she can help it.
We finally discover that Ben is a formidable physical threat as well as a Chessmaster when he takes down two Arab soldiers with assault rifles within seconds, armed with nothing but a baton.
Ben: "Oh, so you do speak English!"
In a flashforward, Sun confronts her father and tells him that she knows what he forced Jin to do so they could get married, and reveals that she used the Oceanic lawsuit settlement money to buy controlling shares in her father's company. As he's taking this in, she very coldly assures him she will do what she wants. The amount of barely-concealed rage in her voice and shown on her face is especially jarring.
Juliet's fight with Charlotte in "The Other Woman".
The Monster's incredibly badass attack on the soldiers in The Shape of Things to Come, where it's larger, faster, deadlier, and just generally cooler than ever before.
After being shot, Locke fully recovers (but temporarily becomes paralyzed again), and decides to shoot himself in the head because he can't move his legs. Walt, who isn't even on the island, appears and stops him. The man of 400 knives later gets up, walks to the radio tower, and chucks one of his weapons into Naomi's back.
In "There's No Place Like Home, Part 1", Ben calmly walks towards Keamy and his men to bring them away and let Locke get into the station. ''Of Mice and Ben'', indeed.
"My name is Benjamin Linus. I believe you're looking for me."
Sawyer jumping off the helicopter in order to give the Oceanic Six the chance to make it to safety—quite possibly the first truly selfless thing Sawyer has ever done.
Sayid's fight with Widmore's assassins in the Season 5 premiere. He throws one of them onto the stack of knives in his dishwasher, after being hit by a double dose of horse tranquilizer.
Hurley turns himself into the cops and faces three counts of murder rather than go with Ben. Granted, this time he probably should have gone with him, but at this point it totally serves Ben right that someone completely refuses to believe a word he says.
Hurley saves up to 78 lives in one fell swoop when he buys the remaining seats on the Ajira plane.
When asked by Jack whether the passengers on Ajira 316 would die in the crash they were planning on causing, Ben, while hardly looking up from his book, replies with a nonchalant "Who cares?".
Frank Lapidus landing Ajira flight 316.
Sayid shooting young Ben may have been a very dark moment for him, but there's no denying it was cathartic.
"You were right about me. I am a killer."
Ben's Oh, Crap! face when he wakes up to see the very much alive John Locke smiling down at him at the end of "Whatever Happened, Happened". It's not even negated by the fact that it later turns out to not really be Locke
"Hello Ben, welcome to the land of the living."
Ben blowing away Caesar mid-speech with his own shotgun. "Were you looking for this?" BLAM!
The Reveal of what happened between Desmond and Ben in "Dead is Dead". The audience had been given plenty of reasons to fear for Desmond and Penny after seeing out of context scenes of Ben covered in blood at the dock and the ominous moment where he tells Sun to tell Desmond he's sorry if she ever sees him again. It turns out that when Ben tried to kill Penny, Desmond beat the crap out of him and tossed him off a dock, with only one arm, seconds after Ben shot him.
The Monster plays Ben like a fiddle in "Dead is Dead", in a way that only becomes obvious in retrospect. It takes the form of Ben's daughter, and viciously gets him to knock off his scheming against Locke and do whatever Locke says from now on. Only it later turns out both Alex and Locke were actually the Man in Black/Smoke Monster all along, so this was all just one big Kansas City Shuffle by him, and it worked perfectly.
Dr. Chang easily outwitting Hurley in "Follow The Leader".
Dr. Chang: Your friend Faraday said that you were from the future. I need to know if he was telling the truth.
Hurley: Dude, that's ridiculous.
Dr. Chang: What year were you born? What year?
Hurley: Uh... 1931?
Dr. Chang: You're 46?
Hurley: Yeah. Yes, I am.
Dr. Chang: So you fought in the Korean War?
Hurley: ...there's no such thing.
Dr. Chang: Who's the President of the United States?
Hurley: ... All right, dude, we're from the future. Sorry.
All seems lost as the plan to erase the entire timeline that the whole second half of season five was leading up to fails as the nuke doesn't go off. Except Juliet survives falling dozens of feet, then uses every bit of strength remaining in her battered body to whack the thing with a rock until it goes off.
"Come on, you son of a bitch!" * fade to white*
"Locke" revealing himself as the Man in Black/Smoke Monster and killing Bram and his followers in seconds.
After Richard asks for an assisted suicide, not being able to kill himself due to being touched by Jacob, Jack puts some pieces together and realizes there's a chance the same applies to him. He proceeds to test it by lighting some unstable dynamite and waiting along with Richard, all while asking him some good questions for once and also venting about having been manipulated into this for his whole life.
After being MIA for the entire fifth season, Claire reintroduces herself by blowing away two Others with a high-powered rifle.
The Man in Black's attack on the Temple, killing most of the Others and sending the rest into hiding within minutes. And earlier that day, when he nonchalantly shrugged off Sayid's huge dagger to the chest and proceeded to recruit him with just a few sentences.
Claire, Sayid, and Kate walk through the destroyed temple at the end of "Sundown" while "Catch A Falling Star" is playing. Not to mention the fact that this song seems to be a new Nightmare Fuel of Lost.
The flash-sideways Jin scores one when, after spending a whole episode appearing to be just like the regular version when it comes to violence, he disarms one of Keamy's thugs with efficient, precise martial arts moves before giving him a Moe Greene Special. And not just any thug, but the very same Mikhail. Same eye, too.
Flash-sideways Sawyer (or James Ford, as he became a cop instead of a con man) heads with his partner Miles to arrest Sayid. Sayid convinces his sister-in-law Nadia to stall Miles while he heads out the back door...but finds that Ford had anticipated this and had prepared a trap with the house's garden hose.
In "Ab Aeterno," when Richard says aloud he's "changed his mind," meaning he wants to side with the Man in Black, Hurley arrives and relays the words of Richard's deceased wife Isabella to Richard. While the scene is slow and more of a Heartwarming Moment, the real kicker comes at the end of Hurley and Richard's conversation. Hurley has a concerned look on his face and Richard asks if something's wrong. Hurley says Isabella has one more message. Richard has to stop the Man in Black, from leaving the island, because if he doesn't, "...todos nos vamos al infierno." Which, for non-spanish speakers, means "We all go to hell."
Jacob kicks Richard's ass in "Ab Aeterno". For a guy who had, thus far, basically sat around doing nothing, that was pretty hardcore.
Richard: I'm already dead.
Jacob: * proceeds to drown Richard*
Richard: * between gasps* STOP!
Jacob: What's that?
Richard: I want to live!
Jacob: That's the smartest thing you've said so far.
The Man in Black throughout "The Candidate". Specifically? He proves himself to be immune to bullets and have ridiculously good aim, and kills at least 8 of Widmore's mooks, one of whom with his bare hands. Then he tricks Jack into bringing aboard a bomb, which leads to the deaths of Sayid, Jin, and Sun. Then he goes out to personally kill Kate, Jack, Sawyer, and Hurley. He also uses Claire's delicate emotional state to recruit her back to his side like a master and Nonchalantly slits The Scrappy Zoe's throat after Widmore demonstrates how pointless she really was.
Jack knocking the Man in Black into the water. As it turns out, it was part of the Man in Black's plan all along, but it still took some Brass Balls to attack an Eldritch Abomination like that.
Man in Black: Whoever told you that you needed to stay had no idea what he was talking about.
Jack:John Locke told me I needed to stay. (pushes him into the water)
Jack seeing through the Man in Black's Batman Gambit to get all the candidates to kill each other. Shame that Sawyer didn't listen, but the fact remains that Jack saw through the plan of the same man who was able to make Ben Linus his Xanatos bitch.
Sayid's Heroic Sacrifice, in which he helps to save as many of his friends as he can by running as far as he can while carrying a bomb doomed to detonate. Also, he manages to tell Jack where to find Desmond (confirming that he successfully lied to the Man in Black's face about killing him) and what he needs to do next to stand a chance in hell of defeating the Man in Black.
Rose gets one in the finale by fearlessly standing up to the Man in Black.
Jack: You're not John Locke, you disrespect his memory by wearing his face, but you are nothing like him. It turns out he was right about just about everything. I just wish I could have told him that when he was still alive.
The final fight between Jack and the Man in Black. Some of the other fight scenes may have been better through choreography or other aspects, but the final fight became pure, untainted awesome through location alone: on a collapsing cliffside during a thunder storm.
Kate was generally considered a Creator's Pet on this show, but give the woman credit: she went back to the island in order to bring Claire home, and that's exactly what she did. The moment she grabs Claire's hand in the Ajira as it takes off, the fact that her "awakening" in the Alt-Verse was delivering Aaron, and the fact that ultimately the character of Kate wasn't defined by her Romantic Plot Tumour: that was pretty awesome.
Frank. After spending most of his time on the show just tagging along after everyone else, finally gets to FLY THAT PLANE OFF THAT ISLAND after using little more than spit and duct tape to put it back together.
After spending almost his whole life as a Cosmic Plaything on-top of not being taken seriously by the other characters, Hurley becomes the new caretaker of The Island.
Locke getting the last line of the series: "We've been waiting for ya."