Superman Movies: Classic Films
The definitive Christopher Reeve era represents the golden age of Superman cinema, anchored by Richard Donner's masterful vision and Reeve's excellent embodiment of both Clark Kent and the Man of Steel. This watch order uses The Richard Donner Cut of Superman II to maintain narrative consistency with the first film's tone and character development.
Supergirl is included as it takes place in the same universe, though it functions more as an optional spin-off since Superman himself doesn't appear.
There are 3 other watch orders available – see the links up above.

Superman
Mild-mannered reporter Clark Kent must embrace his superhero identity as Superman when the villainous Lex Luthor threatens to take over the world.

Superman II: The Richard Donner Cut
Superman faces a difficult choice between love and duty when he must decide whether to give up his powers for Lois Lane while three dangerous Kryptonian criminals threaten Earth.

Superman III
When a wealthy executive hires a computer genius to create synthetic kryptonite, Superman faces unexpected psychological effects while battling a powerful supercomputer. The Man of Steel must overcome these challenges while reconnecting with his past in Smallville.

Supergirl
Superman's cousin Kara comes to Earth on a mission to retrieve a powerful orb, but finds herself battling a dangerous witch in this superhero adventure.

Superman IV: The Quest for Peace
Superman embarks on a mission to eliminate nuclear weapons from Earth, but his efforts are threatened when Lex Luthor escapes from prison and creates a powerful enemy called Nuclear Man using Superman's DNA.
Related Film Series
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.
Highlander
An immortal Scottish warrior battles through the centuries in this cult fantasy franchise about sword-wielding Immortals who can only die by beheading.
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.