Was it a dream? Was it a hallucination? Is anything in the world actually real? These are the fundamental questions that many filmmakers have tackled from the beginning of cinema to regale audiences with mind-bending twists and confounding tales.

The concept of “was it all a dream” is a common trope in films that can help characters learn crucial lessons, find hidden truths, unveil dark secrets, or simply find the meaning of life. Movies like “The Wizard of Oz,” “A Nightmare on Elm Street,” and “Inception” take audiences on wild rides in which guessing what is real is part of the fun and the mystery of the film.

While some movie critics deride the dream concept as a cop-out that allows a movie to get away with certain plot holes, audiences can never seem to get enough of them as everything from “The Matrix” to “La La Land” allows viewers to lose themselves in other worlds for a couple of hours.

To find a comprehensive list of movies that tackle the question of reality, Slumber Yard compiled IMDb data from June 30 on movies with dream twists or reality-altering endings and organized them chronologically.

The movies on the list are filled with all-time classics, littered with A-list actors, and filled with the best directors in movie history. Some of these movies have won major awards, such as “The Discreet Charm of the Bourgeoisie,” which won the Oscar for Best Foreign Language Film.

If you’re into movies that delve into the subconscious and keep you guessing all the way until the end, you’re going to love this list. But be warned: This list is filled with spoilers and reveals all the secrets and twist endings. So, if you haven’t seen these movies, get streaming, and come back to see if your favorites make the list.