Please don't list this on a work's page as a trope. Examples can go on the work's YMMV tab.
Tear Jerker: Alfred J. Kwak
The death of Alfred's parents and all of his siblings at the start of the second episode. Alfred runs off on his own again just before the others cross a busy highway, prompting Henk to run after him. Disaster strikes, as a car comes out of nowhere and runs over the lot of them, and Henk stares in horror at the scene before him. Alfred then innocently walks up to him and asks "Where's mommy? Where's daddy?" Without saying a word, Henk then just hugs him to comfort him.
After Alfred gets back the Chess Queen's crown from Dolf, he runs up to her to return it, only to find that he's too late; the sun is rising, meaning she will never be able to come to life again. Regardless, the Chess Queen happily accepts her fate, and spends her final moments marveling at the sunrise with Alfred. The music in this scene adds a lot to how heart-rending it is.
Chess Queen: I've long dreamed to one day see the sun rise, and to be able to see it with my own eyes. How beautiful...
During a hectic journey at sea, Alfred is thrown overboard and sinks beneath the waves, apparently drowning. He then has a near-death experience, dreaming that he's turning into various animals and wandering around different places, looking for Henk, all the while crying out that he doesn't want to be alone. Surreal and heart-breaking at the same time.
When Dolf takes over Great Waterland, he kicks King Franz Ferdinand out of his castle, and Ferdinand is forced to leave the country with his closest servant. As their car breaks down they sit down by the side of the road, and Ferdinand voices his regret for allowing things to get so far out of hand in his country that it would allow a megalomaniac to seize power. As his servant tearfully says "But Your Majesty...", Ferdinand simply says he doesn't have to call him that anymore, since he's no longer a King.
When Alfred and Paljas have fled a planet inhabited by one crazed robot, Alfred looks down from their ship to see the robot with its arms stretched out to them and wonders if maybe it just was lonely and wanted to keep them as company.