The Metroid series is one of Nintendo's biggest franchises, as well as one of their darkest properties in terms of content. The series follows the iconic bounty hunter Samus Aran as she explores foreign planets, faced with extraterrestrial threats. The games also boast Nintendo's most consistent narrative across a variety of consoles.
Due to the franchise's narrative continuity, many Metroid characters develop fleshed-out backstories throughout the series. Spin-off titles and manga adaptations also fill in the gaps that the mainline games don't cover. These characters who appear throughout the Metroid games have the most compelling backstories in the series.
10 SA-X
Samus has come across many enemies throughout her interstellar travels, but none are as frightening as the ones who mirror her own image. That's definitely the case with SA-X, who serves as the main antagonist of Metroid Fusion for the GameBoy Advance. The character even influences the events of Metroid Dread on the Switch.
SA-X was created after an X-Parasite infected parts of Samus's iconic orange Power Suit. From there, the parasites evolved into a clone of Samus while at a research station. SA-X later broke out of quarantine and began hunting down the real Samus, equipping an Ice Beam to capitalize on Samus's weakness to cold.
9 Raven Beak
It's surprising that the most recent installment in the series, Metroid Dread, is one of the few titles to introduce characters to a Chozo character. The Chozo race is notable in the franchise for being the bird-like sages who created Mother Brain. Raven Beak, a Chozo leader, serves as the main antagonist of Metroid Dread.
As it turns out, Raven Beak's ties to Samus Aran are closer than one would expect. After Samus was adopted by the Chozo race on the planet Zebes, Raven was one of the Chozo who volunteered to infuse Samus with their DNA. Therefore, Samus confronting Raven in the new game finds her facing off against her own creator.
8 Sylux
Little is known about Sylux, one of six bounty hunters who debuted in Metroid Prime Hunters for the Nintendo DS. However, the character seems to be important to the future of the franchise. Sylux's ship appears in a Special Ending of Metroid Prime 3: Corruption and the character also cameos at the end of Metroid Federation Force.
Seeing as Sylux will likely appear in the upcoming Metroid Prime 4, his backstory may be further revealed. As far as fans know, Sylux harbors hatred towards the Galactic Federation and Samus by association. This enigmatic origin definitely leads many fans to believe that Sylux's history with the Federation gets pretty personal.
7 Weavel
Another bounty hunter who appears in Metroid Prime Hunters is Weavel, a Space Pirate. Samus has a long history of fighting the Space Pirates, so it makes sense that she and Weavel have bad blood. However, Weavel's appearance in Prime Hunters is the culmination of a long-held grudge against Samus.
Apparently, Weavel was once a Space Pirate warrior who was left for dead during a battle with Samus on Brinstar. He was saved by an experimental procedure that converted most of his body, except his brain and spinal cord, into a cybernetic armor. Weavel continues to work for the Space Pirates, with his goal set to kill Samus.
6 Anthony Higgs
Remember him? This Galactic Federation soldier first appeared in the Wii game Metroid: Other M. Higgs was once part of the same Federation Army unit as Samus, where the two became friends. Due to their close rapport, Higgs gave her the nickname "Princess" as a joke towards her defiant and tomboyish personality.
Samus and Anthony's camaraderie ended when their leader, Adam Malkovich, lost his brother Ian due to a ship malfunction. While the experience caused the guilt-ridden Samus to leave the Galactic Federation, Anthony chose to stay. The two eventually reunite during the events of Other M while investigating the BOTTLE SHIP.
5 Mother Brain
Mother Brain is one of the most prominent antagonists of the Metroid series. She appears as the final boss in several games of the series, including the original Metroid on NES and its beloved sequel, Super Metroid. Surprisingly, Mother Brain's creation is very connected to Samus Aran's own origin story.
Mother Brain was originally an A.I. created by the Chozo, the same race that adopted an orphaned Samus. Samus even spent most of her childhood and teenage years protected by Mother Brain. However, after Samus had left the Chozo, Mother Brain turned on them when Space Pirates invaded, ultimately becoming their leader.
4 Dark Samus
The origins of Dark Samus are not dissimilar to those of SA-X. This character, however, appears as the main antagonist of Metroid Prime 2: Echoes and Metroid Prime 3: Corruption. However, the character's origins go all the way back to the original Metroid Prime, directly following Samus's defeat of the titular creature.
After the Metroid Prime absorbed Samus's Phazon Suit, Dark Samus was formed from a combination of human DNA and Phazon. Dark Samus escaped from the planet Tallon IV in search of more Phazon to make it grow stronger. The clone was able to eventually find more Phazon from another dimension, the Dark Aether.
3 Adam Malkovich
Adam Malkovich is one of Samus's closest allies throughout the Metroid series. He first appeared through text in Metroid Fusion, though the character was fleshed out more in Metroid: Other M. As the commander of the Galactic Federation Army, Samus grew to admire the gruff, capable military leader as a father figure.
When Adam and Samus initially met in the Federation Police, they gained a close rapport as colleagues. He would end every order he gave Samus with the quip, "Any objections, Lady?" knowing that she would not disobey him. However, by the start of Other M, Adam is suddenly more cold and disrespectful to Samus.
2 Ridley
No antagonist in the Metroid saga has caused more mayhem than Ridley. This Space Pirate captain appears in most entries of the series, whether in his organic form or as a cybernetic recreation. However, the bloodthirsty dragon's rivalry with Samus goes all the way back to the future bounty hunter's childhood.
During a Space Pirate invasion on the planet K-2L, Ridley was approached by a three-year-old Samus Aran. Though Samus naively tried to befriend the dragon, Ridley went on to brutally murder her parents only moments later. At this moment, Ridley unknowingly set his future archenemy on a path to destroy him.
1 Samus Aran
It's difficult to find a character in the Metroid franchise with more time to develop than Samus Aran. The iconic bounty hunter has appeared in every single installment of the series. Her origin story also ties her in with many of her future antagonists and allies throughout the Metroid series, including Ridley and Raven Beak.
Samus was orphaned after Ridley attacked her home planet, K-2L. She was later adopted by the Chozo on Zebes, where she first encounters Mother Brain. Eventually, she joined the Galactic Federation and became a highly-skilled soldier. Now a bounty hunter, Samus has made friends and foes all across the galaxy.