For more than 30 years, the Metroid Series has raised the bar for science fiction action-adventure games. The series' combination of excellent level design, immersive atmosphere, and intense action has resulted in many unforgettable experiences.
The series has also had some excellent and highly memorable boss fights. While a challenging or unique boss fight is great in its own right, what can make a boss especially memorable is if it ties in with the series lore. The Metroid series features plenty of such fights, and this list will recount some of the best. These are the bosses with the best lore in the Metroid series.
6 Ridley
A staple of the series ever since its first entry in 1986, Ridley is perhaps the most personal antagonist that series heroine Samus Aran has ever faced. As the original leader of the space pirates, Ridely is responsible for causing death and destruction on a galactic scale. Most notably he is responsible for the massacre of the colonists living on planet K-2L.
The sole survivor of the massacre was a young girl who would end up being adopted by the Chozo and eventually became the greatest bounty hunter in the galaxy. As in many classic tales, Ridley is ultimately responsible for creating his own nemesis. Samus would end up fighting and defeating the space dragon numerous times and even canonically killing him in Super Metroid.
5 Mother Brain
Mother Brain was originally created as an organic supercomputer by the Chozo. However, after coming into contact with the space pirates she would ultimately turn against her creators. She then took control of the space pirates and attempted to conquer the galaxy.
Mother Brain is yet another villain connected to Samus' past as the two knew each other before Mother Brain went rogue. All of this makes it especially satisfying when Samus finally put an end to her once and for all at the end of Super Metroid.
4 Raven Beak
The primary antagonist of Metroid Dread, Raven Beak is the leader of the Mawkin Tribe, a clan of Chozo warriors with plans for galactic domination. It is revealed throughout the course of the game it was his Chozo DNA that was infused into Samus as a child, making her something akin to his daughter. He is also responsible for massacring the Thoha tribe who had originally created the eponymous parasites and had planned to utilize the power of the Metroids to take over the galaxy.
Needless to say Samus' extermination of the Metroids in Metroid II: Return of Samus through a wrench into that plan, but Raven Beak would strike back by luring Samus to the planet ZDR and sending the EMMI robots to try and kill her.
3 Metroid Prime
Refered to as the "Worm" in Chozo writings, the eponymous Metroid Prime was a Metroid of unknown origin that would end up being heavily mutated by the Phazon infecting the planet of Tallon IV. Later it would be detected by the scans of the space pirates who would give him that name. After being defeated in the first Metroid Prime game the titular creature would return in the form of Dark Samus, serving as the primary antagonist for the rest of the trilogy.
One interesting way that Metroid Prime is tied into the lore is how throughout the series players continually see the effects of Phazon mutation on Metroids and how it affects their physiology. Through this players are able to get a sense of how the original Metroid Prime came to be.
2 Gorea
From the beginning Metroid Prime: Hunters presented players with an intriguing core mystery. The game is set in the Alimbic cluster which had once been home to a highly advanced alien race who one day suddenly vanished. Throughout the course of the game, it is gradually revealed that the Alimbic had been wiped out by a creature that was able to absorb and appropriate any weapon used against it. In a last-ditch attempt to contain this unstoppable beast the Alimbic sealed it away on a ship in another dimension.
Of course Samus and the other bounty hunters end up unwittingly setting it free where it is revealed to be an alien called Gorea. However in an interesting twist, the game's lore turns out to be the key to defeating Gorea once and for all. By fulfilling the Alimbic prophecy Samus is able to gain access to the Omega cannon, the only weapon capable of killing the beast.
1 Weavel
Throughout the course of the Metroid series, Samus has gunned down countless space pirates, to the point where it is almost routine for her. However one stands out above the rest, and that is the bounty hunter Weavel. Originally part of an elite force of space pirates, Weavel was mortally wounded after an encounter with Samus and outfitted with a cybernetic suit.
From that moment on Weavel dedicated himself to two things, getting revenge on Samus, and gaining more power. One interesting aspect of Weavel's character is that his loyalty to the Space Pirates is somewhat questionable, it has been hinted that given a chance he would betray his former comrades in a bid for more power for himself.