This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Fraggle Rock
Several instances, but "Marooned," "Gone, but not Forgotten" and "Change of Address" (the final episode) especially.
"Just a Dream Away" from the second named episode has lyrics that are particularly profound: Once I wasn't here, and then I suddenly appeared... just like water flowing, I know where I'm going... you got to leave, to stay. Richard Hunt's death does not help matters.
"Change of Address" is one giant case from beginning to end. You'll likely be reduced to mush long before, but Sprocket's whimpering at Doc's words (and Doc's words themselves) that they'll never see Gobo again is the definite breaking point. Of course, mere moments later, they do see Gobo, but it doesn't make the emotional impact any less. And the whole "Magic Be With You"' segment with the tunnel will break you up to and including the very end of the credits.
Gobo's song "Petal of a Rose." Even harder to listen to after Jerry Nelson died.
The song "Goodbye" from the episode "Manny's Land of Carpets": "Goodbye, goodbye, every eye is dry. Leaving? There's no grieving just a rainbow in the sky. Goodbye, goodbye, goodbye."
"Mokey's Funeral" manages to evoke this even when we know from the beginning that Mokey's actually okay.
Gobo: It was Mokey. I'm sure it was Mokey.
Red: No, no, it wasn't her. (tearfully) She's my best friend.
Gobo: Her plan must've gone wrong; an accident.
Red: But... she's my best friend! You don't understand! She's my BEST FRIEND!!!
Junior's song, "And the Joke Isn't Funny Anymore" certainly speaks to this event.
There's an early episode where Gobo is off on some adventure or other overnight, leaving his roommate Wembly alone for (presumably) the first time. The song Wembly sings will haunt you forever.
If "The River of Life" doesn't make you sniffle at least once, you have no heart. Boober stands at the hole to Outer Space, begging the Silly Creatures to stop poisoning the caves, asking if the Fraggles or Gorgs have done anything to upset them. What Boober doesn't know is that Doc and Sprocket are out at the moment, and he's speaking to an empty, uncaring room - except for us.
The episode where Red realizes that all of her talents just don't seem to be as wonderful or important as Mokey's. And instead of becoming angry or spiteful, she craves to be Mokey. The song "Dreaming of Someone" is truly heartbreaking.
The Trash Heap's attendants' interpretation of the situation makes it doubly heartbreaking when they discuss how she thinks everyone likes Mokey more than her, "...especially Gobo!"
"Marooned", especially the way Mokey holds on to Boober's scarf (it fell off when he and Red were trapped in the cave) throughout the episode, as well as Red and Boober's little moments in the cave.
Boober: It's quiet. Maybe they've stopped trying to rescue us.
Red: Yeah, maybe. You know, Boober, I feel kind of giddy.
Boober: Yeah, giddy and tired. You know what that means, don't you?
The moment towards the ending of All Work and All Play when Cotterpin Doozer, having spent the entire episode wanting to be a Fraggle, realizes that no matter how much she wishes otherwise, she's never going to become anything other than a Doozer. The only thing that saves the episode from having a downright Downer Ending is that she manages to find her niche in Doozer society as the Architect's new apprentice.
Outside of the series, one line uttered in an interview that Gerry Parkes gave after the series ended: "I miss my Sprocket."
Pretty much everything about this show, now that Gerry Parkes (Doc) has passed away. The last two episodes, "The Honk of Honks" and "Change of Address", might be the worst, since both episodes featured Gobo finally meeting Doc after five seasonsnote technically four, but the last season was split into two smaller seasons due to Executive Meddling. Keep in mind that Gobo's puppeteer Jerry Nelson (also the voice of Pa Gorg, The Trash Heap and many others) had passed away two years earlier, in 2012; to see their characters onscreen together is almost too much to bear.
The aforementioned "I miss my Sprocket" line becomes more poignant as well.
"The Fraggles Look For Jobs" is a video made by the puppeteers after the series finished production in 1986, and it was shown at the wrap party.note Most of the jokes are In Jokes and name drops of crew members. While it's mostly funny, the very end of the video, where the Fraggles sing about how they'll meet again someday, is gorgeous as well as gutwrenchingly depressing - topped off by someone giving Mokey a kiss at the very end.
The puppeteers stepping out to reveal themselves as they performed the final song as the Fraggles was the show's equivalent of the "taking off the wigs" scene from the final episode of The Kids in the Hall.
The fact that the show wrapped exactly four years before Jim died has some rather eerie parallels.