The numbering in the Amityville series is famously chaotic. Depending on how you count them, the ninth film is often identified as:
Unlike Friday the 13th (12 films) or Halloween (9 original timeline films), Amityville is unique because it is based on a "true story"—or at least, a very famous haunting claim. The Amityville Horror 9
If you're a completionist looking to brave the ninth chapter of this haunting saga: The numbering in the Amityville series is famously chaotic
The original 1979 film focused on the Lutz family and the "Red Room," which was later revealed to be a simple basement closet rather than a portal to hell. The Amityville Horror 9