For being a highly philosophical novel about human nature, the evils of poverty, and the benefits of just revolution, Les Misérables sure has a lot of straight-up badass in it.
Taking it by character:
When most people think of Valjean being awesome, their minds jump to the cart rescue. This editor's favorite moment from him, however, comes much later, during the final battle. La Résistance, who are at this point pretty sure they're all going to die, decide to send the five among them with children home. Problem is, there's only four disguises. Just as it looks like they're going to have to leave one guy behind, another disguise falls from the sky, and there's Valjean, who just overheard the conversation and sacrificed his only way out for the last man.
Valjean carrying the man who was going to deprive him of Cosette, who he had every reason to hate, on his back, in the sewers under Paris, through quicksand.
Valjean's crowning moment may have been far earlier... five words partway through: "You have killed this woman."
His encounter with Montparnasse on the street.
Valjean escaping the Rue de Petit-Pictus in a coffin.
The way he utterly pwns Thenardier and the Patron Minette gang when they capture him and try to rob him, especially when he burns himself with a fire iron without even wincing to show them how badass he is.
Marius, despite being an utter(ly lovable) dingbat throughout most of the story, also has a couple. The first thing he does upon arriving at the final battle is shoot a sadistic policeman about to spear poor little Gavroche. Then, later, he gets the police to retreat from the barricade... by threatening to blow himself up.
Éponine's famous rescue of Marius I believe needs no introduction, but she has an earlier one as well, when she scares her father Thénardier and his gang away from Valjean and Cosette's house during one of Marius' meetings there with Cosette. What makes this even sweeter is that Hugo writes in what must be the 19th Century French equivalent of "Ha ha, you're scared of a girl!" This editor vividly recalls pumping his fist when he read that.
Javert: "Would you like my hat?" Again, to Thénardier, who I'm starting to believe exists solely to make other people look awesome.
Also, one must not forget Thénardier holding a gun up to Javert at point blank range. Javert informs him that he can shoot, but the gun will misfire. Thénardier shoots. The gun misfires.
And when Mme. Thénardier is threatening to throw a huge stone at his face. He mocks her, saying, "What a grenadier! Mother, you have a beard like a man, but I have claws like a woman." She throws the stone, he ducks, and the stone ricochets off the wall and lands at his heels.
It's a pity that line didn't make it in to the film version of the musical. Hugh Jackman most definitely did have claws in a certain other role he played.
Enjolras. Grantaire. Final battle. Wineshop. 'Nuff said.
"Vive la République! I'm one of them!"
Enjolras has been fighting in a battle that has killed most of the participants on his side, and he is completely unscathed. Not only that, but his defiance and readiness to die actually impresses the National Guard.
Monsieur Mabeuf. When Enjolras hesitates to sacrifice himself by putting the flag back into place on top of the barricade, this octogenarian takes the flag and stands at the top of the barricade, waving it and shouting "Vive la République!" This Moment Of Awesome is recognized by Enjolras, who says, "There now is our flag," referring to Mabeuf's bullet-riddled jacket.
Waterloo. All of it.
Monseigneur Bienvenue's conversation with the dying conventionary. For both of them.
Monsieur Madeleine's decision to save Champmathieu from the galleys.
The bishop gets one in the very beginning of the novel when his congregation is shocked to see their bishop on a donkey and he purposely misinterprets the reason for their surprise in order to teach a lesson in humility. And, you know, what he does for Valjean, which brought this reader to tears.
Combeferre's simple response to Marius' long-winded Napoleon fanboy speech: "To be free."
Father Myriel ventures alone through territory controlled by a gang of bandits who have been robbing churches. His sister believes he is Tempting Fate. He gets to a backwoods church and announces he's beginning a certain festival, but everything needed for it was stolen by the bandits. The next day, a basket is found at the door full of priceless church relics, courtesy of the bandits.
And then following that, rather than giving the relics back, he donates them to the poor.
Enjolras executing Le Cabuc for killing a civilian.
Thénardier's escape from prison. He had to rely on supplies left behind by other escapees who weren't taking him into account, and although intentionally vague, it's implied that for a leg of his escape he had to go making death-defying jumps from rooftop to rooftop despite being emaciated, in pain and in the middle of a freezing rainstorm. Sure, in the end they had to get Gavroche to help him get down to ground level, but he had pretty much gone against all odds up until that point.
From "Look Down/The Work Song:"
My name is Jean Valjean!
And Javert's following line: And I'm Javert! Do not forget my name! Do not forget me, 24601!
Valjean's Shut Up, Hannibal! to Javert in Drink With Me: "You are wrong. And always have been wrong. I'm a man. No worse than any man. And you are free. And there are no conditions. No bargains, or petitions. There's nothing that I blame you for. You've done your duty - nothing more." Bad. Ass.
Likewise, Javert's riposte in Confrontation: "You know nothing of Javert! I was born inside a jail! I was born with scum like you! I am from the gutter too..."
"Stars" and "Javert's Suicide."
Say what you will about what he was doing, but Javert's Defiant to the End moment at the barricades was pretty damn awesome, all things considered. "Shoot me now or shoot me later/Every schoolboy to his sport/Death to each and every traitor/I renounce your People's Court!"
Gavroche collecting supplies in the middle of a battle OUTSIDE the barricade. Just to elaborate, a prepubescent kid is going with a bag and collecting ammo in the midst of gunfire until he's dead. Is he scared? Yes. Will he let that stop him? No!