The Metroid Games

These are in story chronological order and not in the timeline release order.

Metroid (1986)

Samus Aran travels to the planet Zebes to stop the Space Pirates from using Metroids that were discovered on planet SR388 as biological weapons. The Galactic Federation located the Space Pirates' base of operation but were unable to succeed. That is when they chose Samus. She explores the planet, travelling through the planet's caverns and eventually comes across Kraid, an ally of the Space Pirates, and Ridley, the Space Pirates' commander. She defates both before finally finding and destroys Mother Brain. Before she leaves the planet, a bomb is placed in the base of operation and destroys everything.

Metroid: Zero Mission (2004)

After defeating Mother Brain, Samus is ambushed by Space Pirates and her ship crashes back on the surface. With her ship and arsenal destroyed and armed with only an emergency pistol, she is forced to infiltrate the Space Pirate mothership to find a way off the planet. She finds ancient Chozo armor more powerful than her original while exploring deep within Chozo ruins. After acquiring the suit, she goes to defeat the Ridley Robot and escape from the mothership before it self-destructs.

Metroid Prime (2002)

Metroid Prime is the first of the Prime Trilogy. Samus receives a distress signal in her new ship and travels to the planet Tallon VI. This time to stop the Space Pirates from exploiting a powerful radioactive substance known as Phazon. Samus discovers that the Chozo had once settled on the planet, and their disappearance, as well as the emergence of Phazon, is due to a meteor impacting the planet decades ago. After ruining a Space Pirate mining operation and collecting the twelve Chozo Artifacts, she is allowed access to the sealed impact crater and able to confront and defeat Ridley before delving deeper into the impact site where she discovers Metroid Prime, a matured Metroid, mutated and corrupted by Phazon. During the final battle against Metroid Prime, Metroid Prime grabs and takes Samus's Phazon Suit from her.

Metroid Prime 2: Echoes (2004)

Metroid Prime 2: Echoes is the second of the Prime Trilogy. Samus is sent to investigate the planet Aether after a squad of GF Marines was lost there. Samus finds them all dead, killed by several creatures, mostly by an evil race called the Ing. The Ing possess life forms, transforming them into monstrous "dark" versions of their former selves to wage war with Aether's dominant race, the Luminoth. Upon meeting the only remaining member of Luminoth, Samus learns Aether has been split into two dimensions by a meteor. Samus agrees to assist by recovering Aether's planetary energy from Dark Aether. By completing this task, she destroys Dark Aether and the Ing that inhabit it. The final boss fights consist of one against the Emperor Ing and Dark Samus. Dark Samus vaporizes in front of Samus's eyes, but as she flees, Dark Samus is shown to reform in outer space.

Metroid Prime 3: Corruption (2007)

Metroid Prime 3: Corruption is the final game of the Prime Trilogy. Samus, along with three other bounty hunters: Rundas, Ghor, and Gandrayda, are brought together in a ship over Norion to discuss a Space Pirate infection sweeping the Galactic Federation supercomputer network, one composed of organic Aurora Unit systems. Having this network shut down allows for the Pirates to engage in large scale combat in an attempt to further spread Phazon. As a battle erupts on Norion's surface, enormous Phazon-based seedships called Leviathans also begin to rain from the sky onto planets in order to begin corrupting them with Phazon. After a skirmish with Dark Samus which left her asleep for a month, Samus is charged with destroying these "Phazon Seeds" and restoring functionality to the Federation's computer network. Samus is told that after the battle on Norion, her body gained the capability to self-generating non-hazardous Phazon, allowing for her to enter a "Hypermode" attack frenzy with her suit's PED (Phazon Enhancement Device). After purging three planets of Phazon (including a Space Pirate homeworld), the Federation locates the source of Phazon - planet Phaaze - which is made entirely of Phazon. As the Federation engages the Space Pirates in orbit, Samus enters the depths of the planet and succeeds in destroying Dark Samus and Phaaze, rendering all Phazon in the galaxy inert and cleansing her body from its corruption. A ship is seen following her into Warp Space at the end.

Metroid II: Return of Samus (1991)

The Galactic Federation considers the Metroid species too dangerous to exist in the world, and after their own failed attempts employs Samus to travel to the Metroid homeworld, SR388, and exterminate the entire species. Samus kills every Metroid (the Alpha, Gamma, Zeta, and Omega Metroids) and the Queen Metroid. Once all are killed, Samus finds an unhatched egg behind the Queen Metroid's chamber. Before Samus could fire upon on the Metroid egg, an infant Metroid hatches and believes Samus to be its 'mother'. After the baby helps Samus escape back to her ship, Samus hands the hatchling over to the Ceres Research Station for study.

Super Metroid (1994)

Just after Samus leaves the Ceres Research Station, Samus receives a distress signal. She arrives where everyone has been killed and Ridley is caught stealing the hatchling. Samus follows Ridley to a rebuilt base on Planet Zebes where the Space Pirates are trying once more to clone Metroids and use them as bioweapons. Samus explores the caverns and caves of Zebes fighting Ridley and Kraid once more along with Phantoon and Draygon before visiting Tourion, the new location of Mother Brain. Samus runs across the Baby Metroid. However, the baby has grown immensely. Samus finds Mother Brain and confronts her, but is almost killed in the battle. She is saved, though, by the Baby Metroid. The Baby Metroid drains Mother Brain of her energy and gives it to Samus before finally being killed by Mother Brain. However, it was able to leave Samus with gift of a supercharged weapon known as the Hyper Beam allowing Mother Brain to finally be defeated. Samus then escapes Zebes during a countdown that leades to the distruction of the entire planet and any remaining Metroids that were cloned.

Metroid: Other M (2010)

Samus receives a distress signal and follows it to a mysterious vessel named the Bottle Ship. There, she encounters a squad of Galactic Federation soldiers, including her friend Anthony Higgs and her former superior officer Adam Malkovich. They find out that the director of the ship, Madeline Bergman, has been conducting research on illegal bioweapons for the Federation. Eventually, Samus finds a survivor who claims to be Madeline Bergman, but is later revealed to be an android with an artificial intelligence duplicating that of Mother Brain, so that the bioweapon Metroids can be telepathically controlled. The Federation soldiers are mysteriously killed by a secret assassin among their ranks. Samus refers to this assassin as "the Deleter". His or her identity is never explicitly revealed in-game. Samus later discovers that these weapons are Metroids that have been genetically modified to remove their weakness to cold, making them virtually indestructible. Adam sacrifices himself to detach Sector Zero, the Metroid breeding area, from the main ship and activate its self-destruct sequence. After defeating a Queen Metroid, Samus finds the real Madeline Bergman, who tells her the truth about the android she found earlier. The artificial intelligence named MB took on a human shape to build an ideal relationship with the Metroids, similar to the one Samus had with the Metroid hatchling.. After developing emotions, MB revolted, telepathically ordering the cloned Zebesian life forms on the ship to attack their captors. MB appears and attacks Samus and Madeline, but is stopped when Galactic Federation reinforcements show up led by Anthony who is the only surviving member of the original squad. Samus, Anthony and Madeline all escape on Samus's gunship. Samus eventually returns to retrieve "something irreplaceable:" Adam's helmet.

Metroid Fusion (2002)

While acting as a bodyguard for researchers on the planet SR388, Samus is infected by a native creature known as the X Parasite, originally the prey of the Metroid species. Doctors surgically remove portions of her armor and cure the X infection with a vaccine created from the DNA of the Metroid hatchling that Samus first saved. The vaccine not only allows her to survive the parasites, but to also absorb them to power up her energy and weapons. She is then sent to investigate a disturbance at the Biologic Space Labs research station, where it is revealed that specimens from SR388 had been carriers of the X parasite. An X mimicking Samus, nicknamed the SA-X, has taken control of Samus's old suit. While trying to destroy the rapidly multiplying X as well as clones of the SA-X, Samus discovers a secret Federation Metroid breeding program. Before Samus can react, the SA-X discovers the lab and triggers a security system that ejects it into space, killing the Metroids. The Federation eventually shifts interest towards researching the X parasite, especially the SA-X's capabilities, and orders the shipboard computer to prevent Samus from destroying it. Samus then convinces the computer, whom she had nicknamed "Adam", that the X pose a threat to galactic civilization. Adam, in a sudden change of heart, suggests that she alter the station's drive to intercept with SR388 to destroy the planet and wipe out both X populations. After fighting one of the SA-X clones and changing the station's drive, Samus races back to her ship, where she encounters an Omega Metroid which seems to have escaped the laboratory breach. The SA-X returns and tries to kill the Metroid, since the ice-beam it has seems to be the only weapon able to damage it, but the SA-X is badly damaged in the battle. Samus absorbs the SA-X parasite to regain her suit's Energy, defeats the Omega Metroid and leaves the station before it collides with SR388.