[8] The filmmaker has stated that the films are origin stories of people with unique gifts, with the intent being to acknowledge that every person has something special about them.

Unbreakable has been labeled the first grounded superhero film,[9] while Split has been called the first solo supervillain origin story,[10] and Hollywood's first stealth sequel.

When M. Night Shyamalan conceived the idea for Unbreakable, the outline had a comic book's traditional three-part structure (the superhero's "birth", his struggles against general evil-doers, and the hero's ultimate battle against the "archenemy").

During filming for The Sixth Sense, M. Night Shyamalan approached Bruce Willis for the role of David Dunn.

Kevin Wendell Crumb has evidenced 23 personalities to his trusted psychiatrist, Dr. Karen Fletcher, although there remains one still submerged who is set to materialize and dominate all of the others.

Compelled to abduct three teenage girls led by the wilful, observant Casey Cooke, Crumb reaches a war for survival among all of those contained within him, as well as everyone around him, as the walls between his compartments shatter.

The same month, Anya Taylor-Joy, Betty Buckley, Jessica Sula, and Haley Lu Richardson were cast in the film.

Following the events of Split, security guard David Dunn uses his superstrength and supernatural abilities to track Kevin Wendell Crumb.

As Dunn and Crumb engage in a series of escalating encounters, Elijah Price orchestrates everything from the background, all the while holding secrets critical to both men.

Bruce Willis, Samuel L. Jackson, Spencer Treat Clark, Charlayne Woodard, James McAvoy, and Anya Taylor-Joy reprise their roles from Unbreakable and Split.

Split is a horror movie, exploring the origin story of a supervillain, while Shyamalan has stated that Glass would have a different thematic feel as well.

[24] Producer Jason Blum has referred to them as "superhero movies", noting that they are very different from Marvel Studios' films.