Dennis pushed Slappy, causing his head to break, killing him.
"It's good to be back in the family again. Ayuk ayuk."
In the tv version of Say Cheese and Die!, Greg Banks not only gets to fight back when Spidey attacks him, but actually succeeds in thrusting him off! (And this was before Ryan Gosling, who played Greg, buffed himself up for the title role of the teen series Young Hercules!)
Tim Jacobus' cover art. Seriously, what do you think was the real reason kids bought these books? For the engaging, well-written stories?
Gabe, the protagonist of The Curse of the Mummy's Tomb, gets one when he uses the mummy hand he's been carrying throughout the story to stop the bad guy.
Later on, the protagonist, Billy, witnesses the mermaid about to be stolen by thieves. He responds by charging headfirst at the thugs, hoping to distract them long enough for her to escape. Granted, it backfires, but this still takes a lot of courage. They're much older and stronger, and he shows no fear whatsoever.
In Attack of the Mutant when Skipper defeats the Masked Mutant by tricking him into turning into acid - the Mutant could turn into anything solid, but if he turned into a liquid he would be locked in that form.
The villain himself gets one withhis entire plan to capture Skipper. To elaborate, the Mutant takes the form of a young girl named Libby to get close to the kid, while his henchman(disguised as him) has captured a super hero. When Skipper finds out, he comes back to the lair, where "Libby" kills the villain, saving his life...before revealing herself as the mutant, explaining the ruse, then moving in for the kill. Up until then,very few villains in the series had displayed this much ruthlessness and cunning.
In "Calling All Creeps", Ricky is forced to put transformation seeds into a batch of chocolate chip cookies so the Creeps (a group of lizard aliens who first met Ricky over the phone) can turn all the kids into one of them. Ricky tries to stop this from happening, but, upon learning that anyone who eats the transformation-seeded cookies will become mindless slaves to Ricky and the Creeps, Ricky (who's been the school Butt Monkey through most of the book) decides to give cookies to everyone, with the knowledge that those who tormented him before will be brainwashed into following his orders. A revenge fantasy (that doesn't involve guns) for the bullied and oppressed at school if there ever was one.
In Go Eat Worms! when Todd pays his sister back for playing a trick on him by sabotaging her science fair project, a giant paper mache robin, by stuffing worms in the beak.
In "Don't Wake Mummy", Jeff single-handedly got rid of the mummy.
"Goosebumps Horrorland: Creep from the Deep", has Billy Deep swimming to the island shore with a busted knee, whacking a zombie pirate in the ribcage with his cane, fending off a snake, and finally taking down the pirate captain. Turns out the cane he was carrying was actually the captain's leg, and he wants it back. Billy's response? He utilizes the spear fishing lessons his uncle taught him earlier, and sends the leg flying into the bastard's chest.
"How I Learned to Fly": Jack and Wilson are scheduled to race each other live on TV, and Jack loses his powers, while Wilson wins again. The awesome part comes when it's revealed that Jack faked losing his ability to fly, so he can go back to being a more-or-less ordinary kid and be with the girl he's had a crush on for a long time, while Wilson is forced to move because he's still trapped being a celebrity
From the television adaptation of The Haunted Mask II, Carly Beth demonstrates how much she has grown as a person since last Halloween by getting the drop on Steve and Chuck when they try to scare her, while Steve laments how she used to be so much easier to scare. This indicates that while Steve and Chuck never really stopped bullying Carly Beth, she stopped taking their crap from an entire year and they've just been pathetically trying to reassert their petty aggressiveness.
Are You Terrified Yet? has Craig Morgenstern getting payback on the kids who kept trying to scare him, and Amy, the girl who, though she meant well, kept putting Craig in those situations without listening to what he had to say. He also managed to team up with one of the kids' older siblings, whom Craig had accidentally knocked over and embarrassed earlier in the book. And no twist ending to muck it up!