The Hills Have Eyes Movies: Classic Timeline
The original Wes Craven timeline consists of his 1977 cult classic and its widely panned 1985 sequel. While the original remains a landmark of '70s horror cinema, the sequel is considered one of the worst horror sequels ever made.
Craven himself disowned Part II, which he only directed out of financial necessity after the poor reception of his previous films. The sequel is infamous for excessive padding with flashbacks to the original film and features a notoriously absurd flashback sequence for a dog. Most fans consider the 1977 film a complete story on its own. You've been warned.
There are 2 other watch orders available - see the links up above.

The Hills Have Eyes
When the Carter family's RV breaks down in the remote desert, they become trapped and terrorized by a clan of savage cannibals hiding in the nearby hills.

The Hills Have Eyes Part 2
A motocross team ventures into the desert to test a new super-fuel, unaware that their guide Rachel has a dark connection to the area's dangerous past. They soon find themselves facing the same deadly threats that plagued previous visitors to this remote wasteland.
Other Film Series
Benson-Moorhead Universe
An interconnected indie sci-fi/horror universe from filmmaking duo Justin Benson and Aaron Moorhead.
Chernobyl
Feature films exploring the 1986 Chernobyl nuclear disaster and its lasting impact on the exclusion zone.
Hannibal Lecter
A psychological thriller franchise following the brilliant and cannibalistic psychiatrist Dr. Hannibal Lecter, adapted from Thomas Harris's novels across multiple timelines and interpretations.
Hellraiser
Supernatural body horror centered on a mysterious puzzle box and the sadomasochistic Cenobites led by Pinhead.
Stephen King
Feature film adaptations of works by one of the most adapted authors in cinema history.
Unbreakable
M. Night Shyamalan's grounded superhero trilogy following ordinary people who discover extraordinary abilities, culminating in an unexpected crossover.