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, and the week-long series intended to help children cope with The Day After (an ABC made-for-television film about life before and after a large-scale nuclear war between the United States and Soviet Union that is filled to the brim with Nightmare Fuel of the high-octane variety) 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...
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.