|Headquarters||Meteor Crash Site|
|Area of Operations||Inner Solar System|
|Enemies With|| Regular Army|
|Affiliated With||Martians (Metal Slug Defense)|
The Invaders are the primary antagonists of Metal Slug 6. They appear as large, toad-like creatures, with bulbous heads and reptilian features. Their technology appears to be organic, as seen when certain vehicles leak a purplish blood-like fluid when destroyed. Certain members of the species are gifted with insect-like wings, and the ability to launch corrosive plasma blasts from their mouths. Their society is hive-based, with rank based on skin color and durability. They are led by the massive "Invader Queen", the final boss of Metal Slug 6. They may very well eclipse the Martians in viciousness. They are also the natural predators of the Martians; Mars People cower and panic when the drones appear.
Drones: The most commonly encountered Invader strain. Able to breed maggot, which slowly home in on a target and explode. Sometimes they spin around, extend their neck, and devour the player. The ones in final mission explode into a bunch of maggot after they have died. Gray in color.
Squad Leader: Pink in color, and much different than other Invaders. Once they appear, they begin to spin around, and then bounce around the field, only affected by walls. They sustains more damage, and split into a bunch of larvae once they died.
Flying Drones: The most common encountered Winged Invader. In the part where some Hunters take place of Mission 4, they spit 1 plasma blast at you. Gray in color.
Elite Troopers: Tan-Peach in color and only founded in Rootmars' route. they spit 3 unguided plasma blast.
Troopers: These Winged Invaders spit 2 unguided plasma blast. Normally found in the air segment of Mission 4, but they are also found coming up the pit once you prepare to start the Rootmars path. Normally green in color, but the ones found in the Rootmars entrance path and in the part where some Hunters take place of Mission 4 are gray.
Squad Leader: a very rare Pink-colored Drone spitting them up to 8 unguided plasma blast.
Flying Parasite: Small, orange octopus-like creatures with the ability to take control of another organism, latching onto the victim's head with its tentacles and turning him/her into a zombie-drone with purple skin. Able to fly. When swooping down to take control a victim, it can also latch on to you if you get in its way. Once it successfully latches on to you, it will suck you dry until you deaths, unlike the NPCs which they control instead of killing.
Friendly Flying Parasite: Purple versions of parasites, who carry items (and, to a lesser extent) supplies, and only seen in Mission 4.
Hunter Walker: Fish-like anti-personnel creatures with four legs with a blue, oval-shaped body. They have a single cyclopian eye in the center of its body, ceasely scanning the area, just below their very large mouth. They are found in the last two missions. On the ground they spit spores three times in a row. However, the ones found in Hive occasionally are on the ceilings and drop eyeballs down at you, regenerating their eyes at an unnatural rate.
There is also a golden version in the hive that does not attack players and yields a 50,000 point reward upon death (one shot kills it). However, it is considerably faster than the other Hunter Walkers.
Hunter Lord: A giant version of the Hunter. It can release bombs across the screen, these giant creature have thick skin, making them immune to any weapon and it's eye is only weak point. The last gray version is totally indestructible, but they don't attack players It is rare and only one is seen in the Invader Hive.
Scavenger: Gray-colored scorpion-like Invader breed found in the subterranean section of Final Mission. They dig with their forearms and become yellow to charge toward a player.
Smasher: One-eyed, red, crablike creatures with four legs and a white chubby body. They spin their legs like helicopters when flying. When a target is below them, they inflate their body and plummet down in an attempt to smash them. They are seen in the Invader Hive.
UFO: An unusually shaped Invader spacecraft used by unwinged Invaders. Attack by firing purple energy laser 3 times in a row, aimed at the player.
Flying Core: Flying Core. An object used by the Invaders that can use waste or meteors as weapons. It can throw single, multiple, or all the objects at you. One was found near the end of Mission 3, and the ones in Mission 4 will fires severals of slow, but powerful energy laser when all the meteors are used or destroyed. The one in the Slug Flyer path will send extra enemies for each meteor destroyed (this only occurs in Hard Mode) such as first having massives hordes of VFOs trying to destroy Slug Flyer, then several additional Parasites, and then 2 Squad Leader Flying Invaders and 2 VFOs. In the Mission 3 first gets waste with green light (moves slow), then it turns with orange light (fast) and when it takes too long, it will get red-lighted waste (very fast). Sometimes it takes control of fishes, shooting at them will be free and you can take it for score.
Super UFO: Indestructible Invader Flying Object, they look like giant rocks. Other than their meteor launchers, they cannot be destroyed, they can also crush you. Many crashlanded IVFO can be seen in mission 3 if you take upper route instead of take lower route.
Crab-Tank: A kind of Invaders walker. Crab-like, it can fire two energy cannons from the nodules in its head. It is also open its head to to fire a large blue bouncing bubble which splits into 3 smaller ones from a cannon underneath its carapace.
Vanguard: A modified crab-tank with two tentacles atop its carapace. It is able to fire oval lasers from its guns in the first segment of the Final Mission, and the ones found in the Invader Hive fire a huge spinning laser from its eye, which can be hard to dodge. It is seen in Hard Mode only. In Metal Slug Attack, there is a "Type-A" Vanguard; it is essentially smaller and weaker than the standard Vanguard, but makes up for it with its fast speed. The Type-A Vanguard was built exclusively for Annette.
Controller: A green robotic variant of the parasite, a specimen of this type can control a host from afar, using a long umbilical cord attached to the victim's neck. It serves as a prelude to the last boss by taking over one of the characters that the player has not selected. The character varies, but each character has different habits.
These Invaders act as spies and observers. They have the ability to shapeshift into human form, but can also transform parts of their bodies to attack or defend themselves. Transformed parts of their bodies tend to be purple in color. When severely injured or killed, they burst into blue flames and melt.
Odette: A mutant created by the Invaders. While she seems relatively quiet and carefree, she is actually their investigator (essentially a spy) to avoid suspicion, since she shares some human-like qualities, though she also has some Invader traits. Odette has powerful combat capabilities but has been instructed to only transform one part of her body to avoid suspicion. She only appears in Metal Slug Attack.
Annette: Another mutant created by the Invaders. She is older and more mature than Odette, and serves as an inventress for the Invaders. Her MSA infobox states that she is quite impulsive and impatient, which was the main cause of the Type-A Vanguard being built. Annette goes to Earth when she hears that Odette is in charge of investigating Earth to reprimand her for her easy-going attitude towards an important project. She only appears in Metal Slug Attack.
Nowan: A mimicry soldier of the Invaders. Unsure of its own identity and name, it took the name Nowan (and the form of the being that called it that). Nowan has the best mimicry skills in the whole army and is capable of using mimicry to turn into anything just by looking at it. Nowan only appears in Metal Slug Attack.
- The Invaders are based on both the Xenomorph aliens of the Alien franchise and Zergs from the Starcraft series.
- In the Final Mission, the Invaders' hive consists of 5 parts. The first part is where the Rebels are present. This is followed by the Hunters' Hive, which you have to dig down to reach. After that is the Invaders' hive, and the Final part is where you fight the final boss.
- Before their official name was given, fans always referred to them as Venusians or, less frequently, Jupiterians.
- In Metal Slug Defense, the Invaders are in the same faction as the Martians.