The "Insidious" movies can be watched in chronological order of their storylines or by their release dates. **Chronological order:** 1. "Insidious: Chapter 3" (2015) - A prequel set before the first film. 2. "Insidious" (2010) - The first film in the series. 3. "Insidious: Chapter 2" (2013) - Directly follows the events of the first film. 4. "Insidious: The Last Key" (2018) - A prequel focusing on Elise Rainier's backstory. 5. "Insidious: Chapter 5" (2023) - Continues the overarching story. Watching in release order is also acceptable but may lead to some plot revelations being less impactful.

While "Insidious" is often cited as one of the scariest films, opinions on the "scariest movie ever" vary widely among audiences and critics. Many consider "The Exorcist" (1973) to hold that title due to its intense themes and cultural impact. Others might argue for films like "Hereditary" (2018) or "The Conjuring" (2013). Ultimately, the scariest movie is subjective and depends on personal fears and experiences. "Insidious" is notable for its supernatural elements and jump scares, contributing to its reputation in the horror genre.