Well, 'The Texas Chainsaw Massacre' and 'The Blair Witch Project' are Halloween movies that are said to have some basis in truth. They build on rumored incidents and urban legends to create terrifying cinematic experiences. But keep in mind, the accuracy of their claims can be debated, and they are mostly fictionalized for the big screen.
A couple of Halloween movies that have roots in true stories include 'The Conjuring' and 'Annabelle'. They take elements from reported cases of supernatural occurrences and present them in a cinematic form. However, it's important to note that these films often add dramatic and fictional elements for entertainment purposes.
Some Halloween movies claimed to be based on true events are 'The Amityville Horror' and 'The Exorcist'. These movies draw inspiration from supposed real-life hauntings and paranormal experiences.