No happy endings.
The Terminator is one of the most celebrated sci-films of all time. Although it was released in the 80's, people from almost every generation can pinpoint where the phrase "I'll be back" came from. The ending of the movie is lauded as one of the best in the franchise, if not the best. In the film, Sarah Connor is destined to give birth to John, a man who leads the revolution against sentient robots in the future. After Arnold Schwarzenegger's killing machine time travels to the past to kill the mother of a revolutionary leader, he is defeated by another time traveler. Kyle Reese travels back in time as well, and saves Sarah while also impregnating her and setting up the birth of John. The twisted part is, if Arnold's Terminator never returned to the past, Reese would have never followed, and Sarah would have never been impregnated. Sometimes, trying to prevent the future causes it.
At the end of the film, Reese sacrifices himself to save Sarah and kill The Terminator. As reported by Slashfilm, producer and co-writer Gale Anne Hurd revealed that the ending was almost changed. “We got notes to end the film before the end of the film,” she stated at a Screamfest Q&A. “Not even have The Terminator rise out as the endoskeleton, but just end with Kyle Reese and Sarah Connor hugging.” The final scene of The Terminator without his manufactured skin and half a body chasing Connor is legendary, and it's hard to imagine the film without it. Luckily, Hurd and director James Cameron ignored the critics after the first screening. The rest is history.