Insidious: The Last Key is a 2018 American supernatural horror film directed by Adam Robitel and written by Leigh Whannell. It is produced by Jason Blum, Oren Peli, and James Wan. It is the fourth installment in the Insidious franchise, and the second in the chronology of the story running through the series. Starring Lin Shaye, Angus Sampson, Whannell, Spencer Locke, Caitlin Gerard, and Bruce Davison, the film follows parapsychologist Elise Rainier as she investigates a haunting in her childhood home.

Leigh Whannell is an Australian filmmaker and actor. He is best known for writing films directed by his friend James Wan, including Saw (2004), Dead Silence (2007), Insidious (2010), and Insidious: Chapter 2 (2013). Whannell made his directorial debut with Insidious: Chapter 3 (2015), and has since directed two more films, Upgrade (2018) and The Invisible Man (2020).