Sources:

Stranger Things
https://www.wired.com/story/stranger-things-internet-questions/
https://en.wikipedia.org/wiki/Montauk_Project

Twin Peaks
https://news.avclub.com/the-1908-murder-that-inspired-twin-peaks-is-becoming-bo-1830569225
https://www.washingtonpost.com/entertainment/hazels-brutal-murder-was-all-but-forgotten-until-she-inspired-twin-peaks/2017/05/10/b0d064a4-31dd-11e7-8674-437ddb6e813e_story.html?utm_term=.6fbc9ef463f1

Dexter
https://en.wikipedia.org/wiki/Manuel_Pardo_(serial_killer)

Hannibal
https://www.thevintagenews.com/2018/10/29/hannibal-lecter/

Kolchak: The Night Stalker
https://en.wikipedia.org/wiki/B%C3%A9la_Kiss

Bates Motel
https://en.wikipedia.org/wiki/Norman_Bates

The X-Files
https://allthatsinteresting.com/real-x-files
https://en.wikipedia.org/wiki/Project_Blue_Book
https://slappedham.com/real-events-that-inspired-the-x-files/

The Twilight Zone
https://www.vox.com/2014/10/22/7034073/five-scary-twilight-zone-episodes
https://en.wikipedia.org/wiki/Gremlin

American Horror Story
https://www.distractify.com/entertainment/2018/09/12/ZKFHHF/is-american-horror-story-based-on-true-stories

The Haunting of Hill House
https://www.bustle.com/p/is-the-haunting-of-hill-house-based-on-a-true-story-the-truth-is-creepy-af-12015375