Inspiration for the movie, real-life multiple-personality Billy Milligan (February 13, 1955 - December 12, 2014), charged with three rapes, was the first person diagnosed with multiple personality disorder to use an insanity defense by reason of that disorder, and also first to be acquitted thus. Milligan had 24 personalities.
It took M. Night Shyamalan 20 years to make the trilogy, Unbreakable (2000) was being developed shortly after the success of The Sixth Sense (1999). Sixteen years later, Split (2016) came out and shortly after it, Glass (2019) was announced.
Excited for Glass (2019) ?