Bart the mother (Ep 3, S10)
Bart the mother is definitely one of the saddest. While the entire episode isn’t sad (none of them are, just parts) it shakes you to the core. Bart is hanging with Nelson at a chuck e. cheese type establishment when Nelson wins a BB Gun. They shoot at cans and eventually get bored, deciding to kill a small helpless bird.
Marge is seriously disappointed and scolds him. The bird dies and they later find a nest full of eggs, which turn out to be an invasive species of bird-eating lizards. Bart takes care for the eggs and later the lizards. This is sad to many of us because some did similar things in childhood.
One Fish, Two Fish, Blow Fish, Blue Fish (Ep 2, S11)
After eating a poisonous blowfish at a Japanese restaurant, Homer thinks he only has 24 hours to live; all due to the incompetence of a cook! Eventually, he makes it, but he’ll give you some scare.
Bart gets a deuce (Ep 1, S2)
As we all know, Bart in almost every series gets a deuce. But what makes this episode so sad is that this time the guy really tried not to get it. Bart here is a desperate boy who hopes for a miracle and makes everything to reach the goal – do not fail the test and go to the next class.
Bart stops having fun, to study, suffers, sitting at the textbooks and croaking himself for not doing it before. Such an episode simply had to end well and really ended, but it still clings to and overtakes a melancholy: because a truly experienced Bart is a rarity.
See yourself as a character in the famous cartoon
Barthood (Ep 9, S27)
Barthood is The Simpsons parody of the movie Boyhood. While it doesn’t have a central plot, it revolves around Bart’s life after age 10. It shows his relationship with Grampa, before and after death, and explores his true feelings about his family and friends. Wonderful episode, but it really made me think about how far the show had come.
The Squirt and the Whale (Season 21, ep 19)
Lisa befriends a beached whale on the shores of Springfield Bay and must deal with the inevitable heartbreak when the whale dies. The show has never dealt with death more sensitively or movingly.
Round Springfield (Season 6, ep 22)
You will definitely cry. Lisa’s jazz-loving mentor gives her the strength to play her school concert. Excited, she runs back to the hospital to tell Bleeding Gums—only to find he’s already passed.
Mother Simpson (Season 7, ep 8)
This is the episode where Homers long lost mother Mona Simpson returns to the fold. When Mona Simpson comes upon homer in homers own grave and shouts at him you first realize that she thought her son was dead, she came out of hiding to mourn only to find him still alive, whilst at the same time homer himself realized that his mother is there in front of him, for the first time in his adult life.
Although they don’t get long together finally Mons has to go on the run again leaving homer alone. This picture shows the moment that is the saddest moment in the Simpsons show!
Four Regrettings and A Funeral (Season 25, ep 3)
This one’s the saddest because it includes an in real life death (Marcia Wallace) the episode itself won’t make you cry on its own but the loss of Mrs. K will.