Highlander Movies: Release Order
The Highlander franchise follows Connor MacLeod, an immortal Scottish warrior caught in an eternal battle where "there can be only one." The original 1986 film established the mythology of Immortals who absorb each other's power through combat, but the sequels took dramatically different approaches to continuing the story.
This watch order includes all four theatrical releases, though be aware that the franchise suffers from significant continuity issues between films. Highlander II introduced controversial alien origins that many fans reject, while Highlander III completely ignores the second film. Endgame connects to the TV series Highlander: The Series and may require some familiarity with that show's characters and mythology for full appreciation.
There are 2 other watch orders available – see the links up above.

Highlander
Connor MacLeod discovers he is immortal after surviving a mortal wound in 16th century Scotland, beginning a centuries-spanning journey that leads to a final confrontation in modern-day New York City.

Highlander II: The Quickening
In a dystopian 2024 where the ozone layer has been destroyed, immortal warriors MacLeod and Ramirez must battle enemies from their alien homeworld and a corrupt corporation to restore the planet's atmosphere.

Highlander III: The Sorcerer
Connor McLeod must face off against Kane, an evil immortal sorcerer who emerges from centuries of imprisonment to wreak havoc in the modern world. The Highland warrior must use skills learned from an ancient Japanese mentor to stop this powerful enemy.

Highlander: Endgame
Immortals Connor and Duncan Macleod must join forces to defeat Kell, an immensely powerful immortal from Connor's past who leads an army of deadly swordsmen. Realizing neither can defeat Kell alone, they face the ultimate sacrifice as one must die so the other can gain enough power to stop their enemy.
Other Film Series
Avatar
James Cameron's groundbreaking science fiction saga following Jake Sully's journey on the alien world of Pandora across multiple decades.
DC Extended Universe
DC's shared cinematic universe spanning a decade of interconnected superhero stories from Man of Steel to Aquaman.
Marvel Cinematic Universe (MCU)
An interconnected superhero film franchise that began with Iron Man in 2008 and spans multiple phases building toward epic crossover events.
Mortal Kombat
A martial arts fantasy franchise based on the popular video game series about interdimensional fighting tournaments.
Pacific Rim
A sci-fi action series about humanity's war against giant interdimensional monsters using massive humanoid mechs called Jaegers.
Superman
The cinematic adventures of the Man of Steel spanning multiple decades, actors, and universes from the classic Christopher Reeve era to the modern DCEU.