The Mars People are the inhabitants of Mars and they have been hiding from us in the underground of the planet. They have been secretly planning to invade and conquer the Earth. By the time of Metal Slug 2, General Morden was trying to contact the Mars People and made a pact with them. They helped him try to conquer Earth and they would rule it together. But then, the Mars People betrayed Morden and tried to destroy the Peregrine Falcon and then conquer Earth. They failed and returned to Mars. By the time of Metal Slug 3, they returned and abducted General Morden. The Peregrine Falcons and Morden's army frustrated their plans once again. In Metal Slug 6, the Mars People joined the Peregrine Falcons to defeat another alien species that feed on the Martians.
The Mars People also appeared in SVC Chaos and in NGBC. In SVC, they were planning to conquer Earth once again, but the Peregrine Falcons stopped them. In NGBC, one of them got stranded on Earth and became a waiter in Osaka. WAREZ then invited him to the tournament, promising him a return to Mars as the prize.
The personality of these baddies is almost impossible to read since they have a completely different culture than our own. But, what can be determined is that they are quite ruthless. Having said that, they are not stupid, and will ally with humans if they face a threat too great to handle themselves.
- Martian Physiology - The martians physiology is completely different from ours. They are squid-like beings with several tentacles in the place of legs and arms. Their physiology makes them extremely agile and acrobatics. They can perform high-jumps and contortions. They are probably stronger than humans.
- Explosive Teleportation - They can teleport themselves by exploding their bodies and appearing somewhere else.
Their fighting style is extremely unorthodox since they use their tentacles, laser guns and even calls other martians and UFOs.
- Metal Slug 2
- Metal Slug X
- Metal Slug 3
- SNK vs. Capcom: The Match of the Millennium - Olympic mode only
- SNK vs. Capcom: SVC Chaos - hidden character
- Metal Slug 6
- Neo Geo Battle Coliseum
- Metal Slug XX
- Metal Slug SV-001 (pachinko)
- Metal Slug 3 (pachinko)
- Metal Slug Mars Panic!
- Metal Slug Defense
- Metal Slug Attack
- SNK vs Capcom: Match of the Millenium - in Akari 's super and in an error screen alongside Li Xiangfei
- The King of Fighters 2002: Unlimited Match - in the NESTS Boss Team ending, on Igniz's side
- The King of Fighters XIII - in the Egypt stage
- The King of Fighters XIV - in the Dream World stage as a balloon
- Neo Geo Heroes: Ultimate Shooting
- Garou Densetsu The Legend of Wild Wolf
- Garou Densetsu Special
- The King of Fighters (pachinko)
- Doki Doki Akazukin
- Nariyuki Quest