In the Metroid series, Space Pirates are a race of sentient, warlike creatures. Originally classified as the Zebesians, it was later found that they came from their own previousely undiscovered Space Pirate homeworld, and not Zebes as first thought. The Space Pirates are known for their raids on starships and planets in order to steal resources, as well as flora and fauna to bring back to their facilities to experiment and test on. Many creatures and plant life acquired in this way are rigorously and cruelly tested upon in an effort to find a use for them as weapons in the Space Pirate army. The Space Pirates are also known for testing on their own species, as noted in the Metroid Prime series, where newborn Space Pirates were exposed to Phazon, many perishing from the tests. Dissent in the Space Pirate ranks leads to quick and brutal execution by superiors.
The Space Pirates frequently ally themselves with other life forms (notably Ridley and Kraid). Space Pirates, as a rule, are quick to support and ally with anyone who they feel will support their cause or benefit them in some way, although when things go awry they are often known to panic and retreat. In the Metroid E-Manga, Mother Brain describes them: "A race that is completely subordinate to a powerful master. Just like worker bees that obey and follow their queen because of a hierarchy. They're a smart species."
The Space Pirates' main goal in the Metroid series is to reproduce or harness the essence-sucking power of Metroids and use it as a weapon.
Space Pirates first appeared as part of the backstory in the Metroid and Metroid 2: Return of Samus manuals, however they did not appear in a game until Super Metroid. In the remake of the original Metroid, Metroid: Zero Mission, Space Pirate corpses appear in the caverns below Zebes, and Samus later encounters live ones in the extended chapters of the game when she infiltrates a Space Pirate vessel in order to retrieve her Power Suit.
The bounty hunter Weavel in Metroid Prime: Hunters is a Space Pirate. His body was destroyed by Samus Aran in a previous battle, and his brain was installed into a cybernetic body.
The Space Pirates as a species have a strange and varied morphology. Many nuances in their forms spread across the entire species, some having reptilian snouts and others fish or insect-like maws, as well as their hands varying from claw-like pincers to having digits and one or more opposable thumbs. Despite their varied makeup, the Space Pirates are implied to be of a single race, and their varied morphology could be seen as early attempts at experimenting on their own species, forming distinct sub-species within its own ranks. The Space Pirates also have a distinct military formation, and different morphologies of Space Pirate are often attached to specific roles befitting their form.
Zebesian Space Pirates
In Super Metroid, Samus encounters these Space Pirates in the lower levels of Zebes. They are insectoid in appearance, and bear a passing resemblance to the more modern Space Pirates found in the Metroid Prime series. Some Zebesian Pirates can be defeated with simple beam shots, although others will block them and must be destroyed by missiles. Their attacks include jumping between walls to ram Samus, and firing lasers from their eyes.
Space Pirate Militia
The weakest form of Space Pirate, the militia first make an appearance in Metroid Prime 3: Corruption. The Militia are mostly made up of slaves and dissenters, stripped of much of their flesh and skin. With their partly cybernetic bodies and single arm-mounted blades, they resemble the standard troopers found in Metroid Prime. Some Militia carry shields that must be ripped off with the grapple beam, or wear weak suits of armor that can be breached easily by missiles.
Space Pirate Troopers
The mainstay of the Space Pirate forces, Space Pirate troopers fit a number of roles in the Space Pirate ranks. The standard Trooper is fitted with an assault rifle and typically an arm-mounted blade, and are encased in chitinous armor. Some Troopers, known as Grenadiers, are armed with a grenade launcher instead of their standard issue assault rifle.
Some Troopers, known as Aerotroopers, fly on jetpacks and pack a more serious payload of missiles and bombs. In Metroid Prime 3: Corruption, they can even swerve to break target lock. Their one weakness, however, is that the fuel of the jetpacks can be set alight (by the Plasma Beam in Metroid Prime, and the Light Beam in Metroid Prime 2: Echoes), leading to an explosion that kills the wearer. In Metroid Prime 3: Corruption, if the fuel is set alight by Samus' weapons she can use the grapple beam to pull it from the Aerotrooper, causing it to fall to its death.
Both of these types of Troopers have varying ranks above their standard one and are reequipped accordingly: Assault Troopers and Aerotroopers being equipped with missile-deflecting armor that can only be breached by Beam weapons, and Advanced Troopers and Aerotroopers, that are weak to missile fire but resistant to Beam weapons, also being able to engage Hypermode, raising their threat level considerably.
In Metroid Prime, some elite Troopers were outfitted with the Space Pirates' attempts to copy Samus' Beam weapons. They were armed with either Power Beams, Wave Beams, Ice Beams or Plasma Beams, and were among the tougher enemies in Metroid Prime.
Shadow Troopers were the first Pirates Samus encounters that had the ability to cloak themselves. Due to the early prototype nature of the cloaking technology used by the Space Pirates in Metroid Prime, the Shadow Troopers carried no ranged weaponry, as the cloaking device drained too much power from their reserves.
Space Pirate Commandos
Pirate Commandos are a distinct subset of the Space Pirate army, being encased in power armor. Commandos were the most elite of the Pirate Troopers, trained specifically to hunt Samus. They are armed with a powerful grenade launcher, and their armor is fitted with stealth devices and powerful shields. Despite their formidable disposition, using the X-Ray visor, Samus can reveal a weak spot on their Phazite helmets, and if she is armed with a weapon that can pierce the armor, like the Nova Beam, the Commandos will drop in a single shot. They often operate in pairs, called 'Commando Units'. In Metroid Prime 2: Echoes, the Ing have a nasty habit of possessing the Pirate Commandos, raising their threat level considerably.
Elite Pirates and the Phazon Elite
The Elites, first appearing in Metroid Prime, were the most successful of the Space Pirates' experiments into breeding Space Pirates that were fused and fed on Phazon. They were much larger and bulkier than a typical Pirate, and only five subjects survived until maturity, one being the Phazon Elite, a more powerful version of the Elite Pirate, and the Omega Pirate, the strongest of them all.
Samus finds the first Elite locked in stasis due to the power of Phazon shortening the lifespan of those it corrupts. The Elites are only vulnerable to missiles and super missiles, as they are fitted with devices that absorb beam weapons. Their movements and attacks are slow, however, and easily avoidable by Samus. They are believed to have been replaced by the more stable Berserker Pirates found in Metroid Prime 3: Corruption.
The largest and most powerful of the Space Pirates' original foray into Phazon mutation, the Omega Pirate was the boss of the Phazon Mines area of Metroid Prime. The Omega Pirate, as well as being armed with wave quake generators, a dual plasma cannon weapon system and a cloaking device, has the ability to regenerate its wounds by absorbing Phazon.
To defeat it, Samus must first destroy the Phazon crystals on its shoulder and knee joints with attacks from either her Beam weapons or missiles. After they are destroyed, the Omega will call for reinforcements and cloak itself, leading to the appearance of multiple Beam Troopers who will act as a distraction while the Omega regenerates. Putting on the X-Ray visor will allow Samus to see the Omega Pirate, who is vulnerable in its cloaked form. If Samus doesn't succeed in doing enough damage to kill the Omega while it's regenerating, its Phazon crystals will regenerate and must be destroyed again.
It is recommended to get rid of the Beam Troopers before attempting this again, as causing the Omega to begin regenerating will cause more to arrive. After it is defeated, the Omega collapses on Samus and dissolves into Phazon, giving her the Phazon Suit upgrade.
Berserker Knights and Lords
Berserker Knights, and their more powerful brethren Berserker Lords, are Space Pirates raised on and mutated by Phazon, the more successful subjects of the earlier Project Helix that created the Elite Pirates in Metroid Prime. They are bestial and show little concern for their fellow Space Pirates, even using them as projectiles. Samus faces the Berserker Lord as the first boss in Metroid Prime 3: Corruption on the GFS Olympus, and again on Elysia.
In both fights, Samus must avoid the Lords shockwaves and melee attacks while firing at the red orbs on its shoulders. Once they are destroyed, the Lord will begin to fire slow-moving projectiles at Samus, which can be shot and reflected back onto the Lord, hitting the Phazon plating on its head. After a few hits in this way, the plating will be destroyed, allowing Samus to fire at its weak point and destroy it. Berserker Knights are destroyed in much the same way, although they don't have red orbs on their shoulders to destroy before they begin firing their projectiles. When Samus gains the X-Ray visor and the Nova Beam, the Knights can be destroyed in a single shot by firing at their weakpoint.
Space Pirate Commander
The Space Pirate Commanders are among the highest ranking Space Pirates on the Space Pirate homeworld. They were originally Space Pirate Commandos that showed exceptional prowess and long service. They wear red Phazite armor, which is much more resilient than typical Phazite armor, otherwise they are armed identically to other Commandos.
The Pirate Commander will appear multiple times as Samus travels through the Space Pirate facilities in Metroid Prime 3: Corruption, summoning Commandos to block Samus' path. She finally confronts the Commander and his team of Commandos as a mini boss outside the entrance to the Leviathan. The Commander will summon four Space Pirate Commandos before teleporting around the arena and attacking Samus. It is advised to kill the Commandos first and then take out the Commander, as the arena is small and full of obstacles, allowing the five Pirates to deal a lot of damage to Samus as they teleport around and cloak themselves. After taking enough Hypermode punishment, the Commander will fall and Samus will be able to access the lift to the final Leviathan.