American History X has one of the most iconic downer endings in film history, and yet, had they gone with the original ending, it not only would have been darker, but it would have been the wrong choice. American History X follows a nonlinear story about the downfall and redemption of Derek Vinyard (Edward Norton), a neo-Nazi whose embrace of white supremacy ultimately lands him in prison. After his incarceration causes him to have a change of heart, he tries to prevent his younger brother Danny (Edward Furlong), who has joined the same gang Derek did, from going down the same path.

https://screenrant.com/american-history-x-original-ending-derek-worse-bleak/