In the pilot, Sydney is being tortured. After cooly telling her torturer that she's the one in control, as she's got "nothing left to lose", he tells her that's not entirely true - she has teeth. A look of terror crosses her face as he pulls out a pair of pliers. As he is about to yank out her teeth, she screams for him to stop, and then tells him... "Start with the ones in the back... if you don't mind." This was only the first of many, many badass moments.
Later she appears to give in and tells her interrogator to write down the following letters "E-M E-T-I-B" then reverse them, having them spell out "BITE ME".
In the 1st season finale "Almost Thirty Years," Will Tippin, a journalist who has uncovered the existence of a secret organization that is pretending to be part of the CIA has been tortured for several days. His torturer has taunted him with sodium pentathol saying that 1 in 5 men are paralyzed by it. The second that his captors loosen his bonds to transfer him back to Sydney, he grabs the needle full of sodium pentathol and jabs it in the neck of his torturer yelling "One in five, you little bitch! ONE IN FIVE!" at him the whole time.
Whats more, we find out in Season 2 that his torturer was that one in five.
Jack Bristow's in the series finale:
Jack Bristow: You beat death, Arvin... but you couldn't beat me. (presses detonator).
Marshall gets plenty gadget-wise.
Hacking the world's most secure... game of PONG in "A Higher Echelon". And then grabbing Sydney, employing Chekhov's Parachute, and jumping out a building with the line "Hello, my name is Marshall J. Flinkman and I'm here to rescue you!"
Rachel Gibson in Episode 8 of Season 5 "Just so we're clear, you approached me. You were the one that was stupid enough to let me into your room, and afterwards, you were the one that wanted to cuddle." Congratulations Rachel, you've just been rescued from the scrappy heap.
Amy Acker's scene stealing turn as Kelly Peyton reaches its apogee in the episode 'Maternal Instinct' when she destroys a helicopter with an RPG.
Which only makes her eventual comeuppance better once the CIA capture her.
Sydney: Now I'm well aware that you're tough, that you've been conditioned to withstand torture. But I have something you don't have. I have your former best friend.
Rachel: And I know what you're afraid of.
[Sydney holds a snake over Peyton's shoulder as Peyton visibly loses her shit]
Sydney: If I were you, I would stay extremely still.
After giving us a whole season of Awesome, Irina reaches her peak when she leaps off the roof of a 30-story building to escape the authorities in "The Telling".
And shoots out ten stories' worth of windows on the way down, slams into the side of the building, swings into a window, eludes an entire squadron of guards, and disappears into the night.
In "The Box" parts one and two, Sloane undergoes unspeakable torture at the hands of McKenas Cole, refuses to give up the pass code Cole wants, laughs in Cole's face, and tells Jack to cut off his finger prevent an explosion that will kill them all.
Sydney to an interrogator in the pilot asking who she works for: "Write this down - E.M.E.T.I.B. You got that?... Okay, now reverse it."
"Reprisal": Sloane is having Marshall tortured by having his finger nails ripped off. He eventually asks Marshall to cooperate citing "You're not cut out for this." Marshall's response?
"You know, I never liked you. I tolerated you, because I had to, you know, because you were my superior and I was afraid of you. And I saw how twisted you were. But now I see you for who you really are. You are a weak, pathetic man. You know, you're right, I'm not cut out for this. But I am thinking about my son. I want Mitchell to look up to me, to be proud of his dad. Which is why, no matter what you do to me I'll never help you. You know what? I got — I got a hangnail, right there on my thumb? You mind working on that one next?"
It's a little bit mean, but Jack's response when Danny calls him to ask for Sydney's hand in marriage is pretty spectacular:
Danny: Sir, I love your daughter and I want to marry her. That's why I'm calling.
Jack: First of all, Danny, the truth is this is just a courtesy call. Like when you say to your neighbour, "We're having a loud party on Saturday night if that's all right with you"; what you really mean is, "We're having a loud party. On Saturday night."
Danny: Mr. Bristow-
Jack: Sydney doesn't give a damn what my opinion is. What interests me is that you do.
Danny: It's just a custom to call the father. That's all this is.
Jack: Well then, I'll tell you what. I may become your father-in-law, that's just fine. But I will not be used as part of a charming little anecdote you tell your friends at cocktail parties so they can see what a quaint, old-fashioned guy Danny really is. Are we clear?
Danny: Yes, sir.
Jack: Good. Then welcome to the family.
After the pure fanservice opening of Phase One, where the mark is making Sydney change from black to red lingerie while she struts up and down for him, she finally gets him alone. She flips him, pulls a garotte out of her bracelet and starts strangling him, while hissing in his ear:
Sydney: What. Was wrong. With the black one? Do you think it's comfortable wearing clothes like this? [as he tries to hit a panic button] This isn't my first day on the job, I disconnected your call button!
Sydney vs. Allison in the Season 2 finale, widely regarded as one of the greatest fight scenes in TV history and aided greatly by the crew's willingness to Trash the Set as they wouldn't be coming back to the house.
One issue has Jameson hire Jessica to find Spider-Man's secret identity. Instead of actually investigating, Jessica uses the Bugle's money to do various charitable causes (volunteer at a soup kitchen, read books to orphans, helping out in an AIDS ward) on the excuse of following up on tips, all under the nose of Ben Urich. When Jameson figures out what's going on, he wants to sue her, but Robertson points out that suing her for her charity work is a PR nightmare waiting to happen; all he can do is call her to fire her and rage at her answering machine while she listens with a satisfied smile.