The Saw_(franchise) has to be one of the most horrific and unsettling movie series going. That's all by design, of course.
https://screencrush.com/saw-mythology-explainer
https://en.wikipedia.org/wiki/Jigsaw_(Saw_character)#Fictional_character_biography
The man who became a monster is a common theme in so many horror movies.
Saw: The Complete History of Jigsaw https://www.youtube.com/watch?v=ncMoQs_HNmY , https://www.youtube.com/c/CZsWorld/videos
Film Theory: How To SURVIVE Saw! https://www.youtube.com/watch?v=hMw6KdOqS3E , https://www.youtube.com/c/FilmTheorists/videos
8 Smartest Decisions Made By Saw Characters https://www.youtube.com/watch?v=t_sZf6Zyt6c , https://www.youtube.com/c/WhatCultureHorror/videos
https://thecinemaholic.com/saw-ending , https://www.youtube.com/watch?v=sxjlksJgq90
https://collider.com/saw-twists-endings-ranked
How to Beat Every Trap in Saw 2 https://www.youtube.com/watch?v=hgMNaNSg9Gc , https://www.youtube.com/c/HitStartYT/videos
The Entire Saw Franchise Timeline Explained https://www.youtube.com/watch?v=r7gvPFnej8w
https://variety.com/lists/saw-movies-ranked-spiral
How To Beat Every Trap In "Spiral: From the Book of Saw" https://www.youtube.com/watch?v=-xv7mVwHEPA , https://www.youtube.com/c/CinemaSummary/videos
Of course, Saw is just part of a huge bundle of this form of entertainment.
https://editorial.rottentomatoes.com/guide/best-horror-movies-of-all-time
https://www.rottentomatoes.com/top/bestofrt/top_100_horror_movies
https://www.indiewire.com/feature/best-horror-movies-all-time-scary-films-1202012183/
https://www.gamesradar.com/best-horror-movies/
https://www.thrillist.com/entertainment/nation/best-horror-movies-ever
https://www.ign.com/articles/top-25-horror-movies-of-all-time
Of course even STAR WARS has its assortment of psycho villains. https://www.slashfilm.com/591520/star-wars-movie-villains-ranked-least-to-most-powerful
https://paranormal-intersection.blogspot.com/search?q=horror+movies
