This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Snow White and the Seven Dwarfs
Right now, "Happy" is only his name.
"Someday My Prince Will Come." Why? Because we know full well, though Snow White doesn't, that back at the castle the Queen is plotting her demise via the poisoned apple. The thought of someone wanting to harm Snow White -a young, gentle person- is heartbreaking.
On top of that, the reprise has Snow White making a pie for Grumpy right before the Queen shows up.
After the chase and death of the Queen, the soundtrack skips to what seems like complete and total silence (save for sound effects) for a full minute; after the musical chaos of the scene up to that point, it's the cinematic equivalent of a punch in the gut. The effect actually carries over into the funeral scene after the dwarfs return home to find Snow White dead even though there's actually very soft organ music playing in the background.
The music during the funeral, "Chorale for Snow White." The piece is all organ in the film proper, but switches to chamber strings partway through the soundtrack version (the latter was also used in post-1962 foreign-language dubs of the film). Neither rendition is any less emotional.
The shots of the Dwarfs crying. Any shot of a Disney character crying is pretty saddening, especially Grumpy, who is far in the corner of the room they're in, and begins to cry just as well.
Grumpy can't even bear to look at her after all the crap he gave her. He had to have been wallowing in guilt over their vitriol throughout the majority of Snow White's stay. After a few seconds, he just completely breaks down sobbing.
What was the last thing Snow White said to him before the Old Hag arrives at the cottage? "Why, Grumpy. You do care." No doubt that was ringing over and over in his head.
Then poor Dopey, who is pretty much the baby of the group, is so upset that he begins to cry into Doc's shoulder. And Doc, who is barely holding back tears himself, can only gently pat Dopey on the back.
Just to hear Dopey cry is heartbreaking, especially considering how he is pretty much a silent character. On top of that, these are the only notable sounds he makes during the movie (save for a few others).
The minor fact that it transitions from the dwarf who neglected her (Grumpy) to the dwarf who loved her the most (Dopey).
There are stories of how Snow White was allegedly the first animated anything to make an audience cry at the premiere. After months prior to the release of people calling the movie "Disney's Folly," saying that an hour and a half of color/animation would drive people mad, etc., a bunch of grown celebrities/film industry members broke down over the sight of a dead cartoon character.
One has to also keep in mind that the story had already elaborated that Snow White wasn'tdead and pretty much spelled out how she would be revived. Despite the film essentially spoiling its own Happy Ending, the dwarfs' mourning is played with such earnest pathos that you can only feel sorrow for them.
Probably the biggest reason this scene was such an effective tearjerker is because, apart from the mourning animals, the scene was played completely straight and realistically, with the exact same atmosphere you would expect at a real-life funeral. No epic soundtrack, no great meaningful speech, no symbolic magical events... just sadness and loss.
It can be hard to tell since they're not wearing their hats, but when the dwarves are surrounding Snow White's coffin and all placing flowers, Grumpy is the one who goes up to put the flowers into Snow White's hands.
After the Prince kisses Snow White, he kneels by her coffin and lowers his head in despair. He himself had no idea his kiss would wake her up.
This doubles as a moment of heartwarming as well, but the scene with the Huntsman when he hesitates to kill Snow White, you can't help but feel bad for him. He didn't want to do it, but he knew it would be his death if he didn't. Regardless, he made her run for it instead.
The reason he has an opportunity to kill her in the first place is because she's attending to a lost baby bird, and thus isn't paying attention to him. The juxtaposition of her kindness and what he's trying to do creates intense suspense, tears, and from there, relief. It had to be rough on the huntsman, too.
Following this he breaks down and begs for the princess' forgiveness, whose reaction is mere confusion, forcing the Huntsman to desperately Shoo the Dog.
When the Queen first gives him his orders, he reacts in horror and begins begging her not to go through with it, until the Queen bluntly reminds him of the penalty of failure.
A minor one, but when Snow White observes the messy house of the Dwarfs after she first arrives at their cottage, she has this thought:
Snow White: You'd think their mother would— maybe they have no mother. Then, they're orphans. That's too bad.
The most Tear Jerking/Heartwarming thing about this movie is not actually a part of the story. In Don Bluth's guide to animation, Bluth himself, a former Disney employee, described the point during production where Disney ran out of money halfway through the film. With no way to finish, he had to go to the bank and beg for another loan in front of a board of executives. As an aid, he brought along fragments of the half-finished film, fragments which astounded the entire board. When finished, the Head Executive got to his feet and made what, for a business man at that time especially, constituted a tremendous leap of faith into the complete unknown:
"Gentlemen, in fifty years time, nobody will remember the names of any of the people in this room. But they will remember the name Walt Disney. I'm in."
Assuming it can be considered canon, Queen Grimhilde's Dark and Troubled Past in the prequel book "Fairest of All". Her actions are still evil, of course, but when you learn why she got that way, it's heartbreaking and puts her into Woobie, Destroyer of Worlds territory.