3/10. "The Inner Light," one of the most crushing episodes of Star Trek: TNG.
In the episode, Picard gets zapped and goes unconscious. In the two minutes that he's unconscious, he lives an entire alternate life in his mind, where he gets a wife, has a family, grows old, and is a happy man. When he wakes up, he realizes it wasn't real. The whole life he imagined was only a momentary dream.
4/10. Sesame Street
On Thanksgiving of 1983, Big Bird learned that Mr. Hooper, one of his friends, was never coming back.
The episode was done on Thanksgiving because producers wanted to air this episode at a time when kids would most likely be with a family member to talk to. They even promoted it beforehand, and warned parents that such a dark topic was coming.
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