Insidious Movies: Release Order
The Insidious franchise is a supernatural horror series that explores the terrifying realm known as The Further, where malevolent spirits prey on the living. This complete release order follows both the Lambert family saga and the backstory of psychic investigator Elise Rainier as original audiences experienced them.
This is the recommended viewing experience for first-time viewers, because the later prequels contain references and character developments that assume knowledge from the original films. The order preserves the intended scares, reveals, and emotional impact while showing how the franchise evolved from the Lambert family's supernatural struggles to exploring Elise's earlier cases and personal history.
There are 2 other watch orders available - see the links up above.

Insidious
When a family's young son falls into a mysterious coma, they discover their home is haunted by malevolent spirits seeking to possess him. They must venture into a supernatural realm called "The Further" to save their child's soul.

Insidious: Chapter 2
The Lambert family continues to battle supernatural forces as they investigate a dark childhood secret that keeps them tethered to the dangerous spirit world.

Insidious: Chapter 3
A teenage girl and her family face supernatural terror as they encounter the dark mysteries of 'The Further,' a sinister otherworldly realm.

Insidious: The Last Key
Parapsychologist Elise Rainier investigates a haunting in Five Keys, New Mexico, only to discover the case involves her own childhood home and dark family secrets.

Insidious: The Red Door
Josh Lambert and his college-aged son Dalton must venture deeper into The Further than ever before to confront their family's dark past and face new supernatural terrors lurking behind a mysterious red door.
Other Film Series
Grindhouse
An exploitation cinema tribute that began as a 2007 double feature and spawned multiple spin-off films from its fake trailers.
Jenna Ortega
An actress known for her horror performances and diverse dramatic roles across independent and blockbuster films.
Nightmare on Elm Street
The iconic horror franchise following the burned child killer Freddy Krueger who stalks teenagers through their dreams.
REC
Spanish found footage horror franchise following a demonic infection outbreak, featuring intense apartment building quarantine scenarios and their devastating consequences.
Silent Hill
Horror films based on the acclaimed video game franchise, exploring the nightmarish town of Silent Hill through interconnected and standalone stories.
Wrong Turn
A horror franchise about travelers encountering deformed cannibals and deadly cults in remote wilderness areas.