This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Mister Rogers' Neighborhood
In terms of the series itself, there are two: The goldfish episode in 1970 (#1101), and the week-long series intended to help children cope with the Cold War in 1983.
The special he made to help children understand and deal with the death of Robert Kennedy. It starts with Daniel Tiger and Lady Aberlin playing with balloons, with Daniel asking if people are like balloons that deflate once their air is all gone. After she answers he asks a new question "What does 'assasination' mean?" Oh, Daniel...
An early episode (#109) from 1968 has Daniel Tiger making a gift for Mr. McFeely's birthday: a glass with his name on it. He shows it to Lady Aberlin, but accidentally breaks it. His reaction is just HEARTBREAKING; even more so that his crying is played out very realistically. There's a full MINUTE (minus 5 seconds) with no dialogue, save for the sounds of Daniel's sobs and the soft piano music in the background.
Fortunately, Lady Aberlin offers to help him make a new one, and even cheers him up by saying that since he practiced with that first glass, the next one he'll make will be even better, turning this into a Crowning Moment of Heartwarming.
In episode #1100 (the one before the infamous goldfish death episode), Elsie Jean cries heavily when she learns that she and her husband, Dr. Bill Platypus, are being forced by King Friday to move away, just because their baby is going to being hatched first.
In episode #53, Henrietta Pussycat, who wanted to play Goldilocks in the Neighborhood play of Three Bears, cries when X the Owl originally wants to replace Goldilocks with his idol, Benjamin Franklin.
While Sesame Street taught children the educational, Mister Rogers focused on the psychological and developmental virtues of childhood. For so many of us who grew up in the late 60ís and 70ís, the success and teachings of both Sesame Street and Mister Rogersí Neighborhood went hand-in-hand and cannot be separated from one another.
Mr. McFeely: (As he comforts the tearful Read-A-Roo) Yeah, I miss him too.
Seriously. People would think this kind hearted man hurt children unintentionally in the long run. Some of the comments that come up from viewers later in the program point out exactly how ridiculous this is.