Tyreese's Last Stand in Issue 14: After witnessing the death of his daughter in a failed suicide pact, he opts to aid the group in taking out a group of zombies in the gym. When entering the gym, he runs straight into the middle of the zombies, killing as many as he can before the group are forced to leave. In the next issue, they return to find all of the zombies dead and Tyreese alive in the corner of the room, casually greeting them.
Carl killing three zombies single-handed.
This is topped later on when he hops out of the back of one of Negan's trucks and blows away about half a dozen of his men with a freaking assault rifle. Negan is so impressed by this he decides to invite Carl into base as a guest just as much as a prisoner.
Rick is held being beaten by an armed bandit while the latter's comrade is preparing to rape Carl. Rick gets so angry he overpowers the bandit and rips his throat out with his teeth.
In the No Way Out arc, Rick is holding off the zombies alone so that Dr. Cloyd can treat Carl's gunshot wound. He's being overwhelmed. Cut to each of the members of the group seeing him fighting alone, and each one of them going out to help fight them. In a series devoid of optimism, this doubles as a Crowning Moment of Heartwarming.
Jesus in his introduction takes on Michonne and Abraham barehanded, while they are armed with their classic katana and rifle. Jesus manages to disarm both, then capture Michonne to use as a human shield.
Jesus on foot armed with a katana against half a dozen Whisperers armed with knives and a flock of walkers. He kills them all, takes a Whisperer as prisoner, and saves his friend.
After the time skip, Carl is jumped by two bullies armed with a brick, who plan to kill Sophia, and mock Carl when he retreats. Carl then immediately comes back once he finds a shovel, and beats (and nearly kills) the two of them while they beg for their lives.
Issues 125 and 126, which conclude the All Out War arc, depicting the climactic show down between Rick, his allies, and Negan's forces. After Negan demands surrender, Rick comes out from the Hilltop to parlay and hits Negan with a positively devastating "The Reason You Suck" Speech wherein he calls Negan out for being a world-class hypocrite and essentially says to him "Hey, maybe if you'd stop being such a murderous prick and actually live up to your rhetoric about rebuilding civilization, maybe we could actually work together and do that instead of killing each other like idiots." But even better? Against all odds and expectations, Negan actually realizes that Rick is right and starts seeing things his way. Then, as soon as his guard is down, Rick stabs him in the neck and triggers the ambush that (in part) ends the war in his favor.
But that's not even the best part. After finally defeating Negan and ending his reign of terror, Rick refuses to let his hated enemy die and actually insists that they save his life. Why? So that they can deliver him to legitimate justice, prove that the new society he's building can be humane to its enemies, and so that Negan will be forced to watch the new world he envisioned thrive without him. After enduring two years of constant tragedy and brutal loss, after watching himself slowly lose his humanity and become little more than a savage, ruthless animal, even a murderer, Rick actually turns it all around. Rather than simply continuing to perpetuate the cycle of violence that he had previously surrendered to, Rick shows immense personal growth and vision, and triumphantly reclaims the nobility of spirit that he had long ago abandoned. Why is this arguably the most awesome of all The Walking Dead's awesome moments? Because after more than 100 issues of brutal, unrelenting cynicism, the story and our hero suddenly rise from the muck to defiantly embrace idealism and optimism despite a world gone mad.
Rise Of The Governor
The Road To Woodbury
Scott Moon killing a zombie trying to eat him and Megan with a pitchfork... all while high as a kite on pot.
Josh taking out a whole mansion full of zombies by pouring alcohol all over the upstairs bedroom and setting it ablaze as he and Lilly escape using a nearby tree growing just outside the window.