Boardwalk Empire/Awesome

Chalky ain't building no damn bookcase.
Margaret profanely telling off Lucy and quitting her job after Nucky sets her up in a fancy apartment.
Jimmy, Al, and Torrio taking out Sheridan and his men.

I think you'll agree that Greek Town belongs to us now.

Van Alden stopping the entire St. Paddy's Day festivities cold and punching out the guy who mouths off to him: "Would anyone else care to interfere with the court-appointed duties of a federal agent?"
- Coupled in the second season when he brings down a restaurant that serves alcohol openly. "This is a raid!"
Richard Harrow sniping the guy who disfigured Pearl from across the street, with pinpoint accuracy in the same spot he shot a rival sniper during the war. And he does it with just one eye. Of course, the pipe organs playing in the background only added to it.
- And there's his story of watching that other sniper for three days waiting for him to take his faceplate off, and finally seizing the one chance he got.
Jimmy returning to Atlantic City and waking up Lucky Luciano with a hot cup of coffee.
- And then Gillian draws Lucky's own gun on him and reveals she's the one who set him up.
Eddie saving Nucky from an assassin (albeit at the cost of an innocent bystander) then shooting him in the leg as he runs away. Quite badass for a character who was entirely comic relief until then.
The Godfather-esque sequence in the season one finale where the remaining D'Alessio brothers are wiped out, as Nucky expertly ties in their deaths toward support for his preferred mayoral candidate as a press conference.
Chalky choking one of the D'Alessio brothers to death was pretty cold but also Badass.
Rothstein's speech about once causing a man to choke to death for his own amusement establishes him as someone you most definitely do not want to get on the wrong side of.
Chalky nailing one of the Klan members who just shot up his club from a good distance away.
Margaret immediately figuring out on her own that she needs to get Nucky's illegal business ledger and money out of his office, and taking them from under the noses of the agents tearing the place up.
- The fact that she's dressed and acts like when she first met Nucky show how far she's come since then.
- She follows this up by returning the money to Nucky, calmly telling him that he should memorize all his transactions from now on and then tossing the ledger into a fire.
Chalky is put into a cell with a bunch of intimidating guys, and their leader is clearly going to make a move against him soon. Chalky just calmly sits pretending to read a book (as he can't actually read) until the right time when he reveals he has connections with all the other prisoners and the "leader" suddenly finds himself without allies in the beatdown that follows. All while Chalky keeps sitting on the bed, not moving a muscle even when the man lunges at him.
- The icing on the cake? The leader is now Chalky's Number Two. That's commanding respect.
Jimmy effortlessly taking down a pair of assassins, one of whom starts with a gun on him from some distance away, with just his knife.
The Commodore lifting an elephant tusk over his head. Particular kudos as it's clear that it requires some effort, so it actually does look impressive rather than him just being unrealistically superstrong.
Nucky throwing the Commodore's dinner to the floor and declaring that he'll destroy him and all his allies. And then openly telling Jimmy just how little his father cared which showgirl he got to sleep with.

I will ruin you. All of you.

Gillian repeatedly slapping the Commodore, getting some revenge for his rape of her.
Margaret forcing Eli out of the house with an empty shotgun. Granted, she didn't know it wasn't loaded, but badass nonetheless.
Jimmy and Harrow scalping one of the Commodore's backers after the man hit him with a cane, in macabre reference to his having survived a battle with the Sioux.
Meyer Lansky talking his way out of the Mexican Standoff between him and Luciano against three trigger-happy guys in Jimmy, Harrow, and Horvitz. The only thing that keeps him and Lucky from being riddled full of holes is his We Can Rule Together plan to team up and overthrow Nucky and Rothstein.
After two seasons of being The Ghost and then an Extreme Doormat, seeing Rose Van Alden not only talk back to her husband for getting Lucy pregnant and thinking Rose would be all right with them keeping the baby, but strike him repeatedly was long overdue.
Owen garroting a man through his fingers.
Nucky announces to the Commodore and all his allies that he's willingly stepping down, and they can run the town again...then tells Chalky it's time for the city's black population to strike due to the racial unrest the Commodore himself stirred up.
- Rothstein's speech that inspired Nucky's plan also qualifies. It nicely summarizes Rothstein's approach to life and business and points out how Nucky can turn things around if he uses the same strategy for his current conflict with Jimmy.

I’ve made my living, Mr. Thompson, in large part as a gambler. Some days I make 20 bets. Some days I make none. Weeks, sometimes months in fact, when I make no bets at all because there simply is no play. So I wait, plan, marshal my resources and when I finally see an opportunity and there is a bet to make, I bet it all.

Dunn Purnsley, when controlling the strike turns round to see at least fifty guys carrying bats and sticks coming to break it up. Does he run? No, he takes his hands out of his pockets and shouts "Hold the line!". Admittedly it doesn't work out too well but all we see of Dunn is him knocking one of the strike breakers to the ground with a single punch before it cuts away.
Manny Horvitz taking out a hitman with a meat cleaver to the head, after he'd taken a shotgun blast to the shoulder.
Jimmy killing his father with his trusty combat knife, with a spear wound that causes him to collapse seconds later.
- And The Commodore, of all people, coming to save Gillian, spear in hand.
Richard and Jimmy's Power Walk into the county office and subsequent engineered "suicide" of Boss Neary.
Esther Randolph's "if it please the court" opening statement over the scenes of Jimmy and Richard killing Neary and Margaret marrying Nucky. Futile, but badass, Madame Assistant U.S. Attorney.