The Invader UFO are the main air troops from the Invader Army. It is composed by an strange flying UFO crewed by a Drone. It can shoot different type of munitions with different damage, color and velocity. They aren't well armored, so they compensate this by flying in formations of six.
They appear during the second part of mission 4 of Metal Slug 6.
- Their flying patterns closely resembles those of lesser enemies from the Gradius games.
- They are commonly referred to as "UFO's", or even "VFO's" which stands for "Venusian Flying Object".
|Human||Rebel Infantry | Arabian Infantry | Japanese Infantry | Pirates | Scientists | Ptolemaic Infantry | Natives | Hunters | Future Rebels|
|Undead||Mummies (Mummy Generator) | Dog Mummy | Mutated Soldiers | Zombies | Tar Man | Clones|
|Mutant||Bat | Chowmein-Conga | Ohumein-Conga | Enormous Moray | Jellyfish | Flying Killer | Man Eater | Huge Locust | Sasquatch | Maggot | Big Snail | Giant Caterpillar | Squid | Huge Ivy|
|Alien||Monoeye | Ring Laser Mecha | Hopper Mecha | Mars Mecha | Mars People | Big Eye | UFO | Mini-UFO | Invader Squad | Winged Invader | Flying Parasite | Hunter Walker | Hunter Lord | Scavenger | Crab-Tank | Vanguard | Smasher | Invader UFO | Indestructible UFO | Flying Core|