Prolific science fiction author Harlan Ellison wrote two episodes of the TV series The Outer Limits, "Soldier" and "Demon with a Glass Head." They both ran during the show's second season in 1964. In 1984, Ellison heard that James Cameron was working on a film that seemed quite similar to the plot of "Soldier," which you can watch in full. Hemdale Productions wouldn't let him see the script. When he saw The Terminator, Ellison was ready to sue.
The lawsuit never came about, because Hemdale Productions settled the case, for money, screen credit in subsequent releases of the film, and a gag order. To this day, people argue over whether The Terminator was at all plagiarized and if so, how much. Read what Ellison had to say about the case at the time and the reaction from James Cameron at Den of Geek. You've probably already seen The Terminator, and it's up to you to watch The Outer Limits episode if you want to form your own opinion.
