The only thing more terrifying than a horror movie is real life, so what happens when the onscreen scares are inspired by true events? Since horror became a genre, authors and directors have been claiming that their works were "based on a true story" to add a little extra color, but usually those claims aren't backed up by a ton of facts. For example, when The Texas Chain Saw Massacre debuted in 1974, producers tried to market it as a fictionalized retelling of something that really happened.