The Simpsons: 10 Utterly Heart-Breaking Moments You'll Never Forget

3. Lisa's Substitute

Few guest appearances in The Simpsons have been as successful, or as engaging as Dustin Hoffman's performance as Mr Bergstrom as far back as season 2. As the atypical teaching substitute, Mr Bergstrom made learning accessible to the usually under-achieving Springfield Elementary students and had such a profound effect on Lisa that she almost immediately became besotted with him.

At the end of the episode when Mr Bergstrom reveals he must move on, Lisa is devastated, and begs him not to leave, professing that she won't be able to go on without him, as no man will be able to replace him as the positive male rolemodel she yearns for. As he sets off to leave, Lisa rushes to the train station to catch him, and confesses the impact his departure will have on him, and his response is both heart-warming and heart-breaking at the same time.

He hands her a note, telling her it contains all she needs to know, which reads simply "You are Lisa Simpson." The episode also features one of Edna Krabappel's finest moments, in a fan-baiting nod to The Graduate in honour of Dustin Hoffman's guest appearance.