This article is part of Yahoo's 'On This Day' series
When James Cameron dreamed about a chrome skeleton emerging from a fire in Rome in 1981, he immediately sketched the image on hotel stationery.
Cameron, sick with fever, was working on Piranha 2: The Spawning, with a famously difficult Italian producer who had fired his predecessor.
But his dream gave him the image of a villain for the film that would make him one of the world’s richest and most famous directors – and Arnold Schwarzenegger into a seriously bankable star.
Watch: At 74, Arnold Schwarzenegger is still the ‘Terminator'
That film, The Terminator, was released on this day, 26 October, in 1984.
Cameron said in an interview with the British Film Institute: "The first sketch I did showed a metal skeleton cut in half at the waist, crawling over a tile floor, using a large kitchen knife to pull itself forward while reaching out with the other hand.
"In a second drawing, the character is threatening a crawling woman. Minus the kitchen knife, these images became the finale of The Terminator almost exactly."
Cameron said he had hoped to create a "definitive" robot story, saying: "It had never really been done."
Made on a small budget of just $6.5 million, The Terminator took $78 million worldwide, despite initially opening in a small number of cinemas.
The film came in part from Cameron’s fears about nuclear war (the robot apocalypse in the film begins with a nuclear exchange that devastates human civilisation).
But it was originally slated to be very different, with OJ Simpson considered for the lead role and Schwarzenegger hoping for the role of resistance leader Reese.
Schwarzenegger said: "It was actually OJ Simpson that was the first cast as the Terminator.
"Then somehow Cameron felt that he was not as believable for a killing machine."
Simpson later stood trial for the brutal knife killings of his ex-wife Nicole Brown Simpson and her friend Ronald Goldman, but was acquitted.
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Schwarzenegger ended up as the Terminator because he became "fixated" on the idea of the robot, and kept offering James Cameron ideas on how the robot should act.
Schwarzenegger said: "He's a machine. So everything has to be matter-of-fact. I told Jim that. I said there should be no joy, no gratification, no kind of victory lap of any sort. Just the mission, complete.
"Jim, afterward, says to me, 'F*ck, you analyse it better than the way I have written it. Why don't you play the Terminator?'"
The first film was so successful that sequel Terminator 2 had the biggest budget in film history, and Arnold Schwarzenegger took his $7 million pay cheque in the form of a GulfStream jet.
In total, the Terminator films (there have been five sequels) have grossed more than $2bn (£1.5bn) worldwide.
Watch: Film prop auction gives fans chance to own piece of movie history