- "Ben 10: Secret of the Omnitrix":
- Ben thinking that Gwen just died. Seeing our hero beating on the ground where she disappeared, screaming, "It should have been me! It should have been me!" is a very emotional sight, even more so when you remember that, despite his being a superhero with countless battles under his belt, Ben is all of ten years old at the time.
- Later, one of his traveling companions asks him how he's holding up, and Ben says that he doesn't know how he's going to explain to her parents that their daughter won't be coming home. Tearjerking from both ends.
- In turn, Tetrax tells Ben his own backstory: As a young Petrosapien, he was a selfish, care-free rogue who only worked for people with power and influence. Then one day, he made the mistake of giving Vilgax a weapon that could annihilate worlds, which the bastard than turned on Tetrax's planet, leaving him the last Petrosapien. Tetrax has spent years trying to stop Vilgax to atone for this. It really makes Squidhead's many brutal, violent deaths over the franchise history all the more satisfying.
- As much of a selfish, misanthropic prick Azmuth acts to the heroes when they find him, his reason why he created the Omnitrix is saddening on a rather broad scale: it was supposed to allow species to better understand each other by seeing through alien eyes. And everyone who comes across Ben wants to exploit the watch for power and destruction. A device that could've united so many worlds, ended so many conflicts, instead becomes the centre of galactic bloodshed by scum like Vilgax. This goes on through the entire franchise.
- The Last Laugh, where Grandpa and Gwen are drained by Zombozo to the point of near death, and Ben is terrified that he can't help because he's afraid of clowns. No child should have to face that.
- Kevin's situation. The kid gets forced to live on the street, rejected by everyone around him, and ultimately becomes a monster because he's unable to get over his image of himself as a "freak". This exchange from Framed really sums up how scared and confused he is on the inside:
Ben: You'd risk hundreds of innocent lives just to get back at me?Kevin: No one's innocent! They just haven't made fun of me yet!
- Similarly, Charmcaster's situation, having to submissively kowtow to a Creepy Uncle who threatens her with magical violence if she steps out of line. It's little wonder that she turns on him in the end.
- The Alliance actually views a darker side in Ben's psyche after Grandpa Max severly injured himself. Rojo's attack pushed Ben to his limits, leading him to run away from Gwen and Grandpa Max believing that everything that has happened was his fault. Along with the finale, this was one of the first season's darkest episode.
Dear Grandpa and Gwen,I care about you both too much to keep putting you in danger. It's better this way.Love Ben
- Back with a Vengeance:
- In the climax, Kevin uses the device to forcefully remove the Omnitrix, not just from Ben's wrist, but from his very genetic structure. It's one thing knowing he gave up the Omnitrix to save Gwen when she was held hostage. But to get a close-up of Ben's agonized face while it's happening is surprisingly shocking and heart-breaking.