The insignia of the Mercenary Corps.
|Enemies||Earth Defense Force|
The Mercenaries had done work for Ultor for at least 15 years. Much of this work included killing people involved in protests, strikes, sick-outs, and even smaller rebellions. Three months prior to the First Martian Revolution, Ultor asked them to return to Mars.
After Capek's death in the Nanotech labs, Ultor secretly sent a message to the Mercenaries, so the Red Faction would not know. Then, a small group of Mercenaries arrived in the Canyon in the Badlands. While Parker and another miner drove through the canyon, they intercepted the group and killed them. Later on, Hendrix informed Parker about the Mercenaries. Soon after, when Parker led his one-man attack on the Comm Center, Mercenaries began appearing all over the complex, slaughtering the remaining Ultor Guards as well as Miners, The faction took over the underground tram system entirely.
Inside the Space Station
Mercenaries took control of the Ultor Space Station, far away from Mars' orbit, which was the housing for the Laser Satellites in Mars' orbit. They set up Mercenary Mecha Turrets, which are the Mercenary variant of Capek Mecha Turrets. The Mercenaries attacked the Red Faction Base, and Eos was captured.
Battle in the Canyon
Mercenaries, as well as a small amount of surviving Ultor Guards, were in battle with the Red Faction. The miners were nearly victorious, until Parker, who had strongly helped them out, was captured at the Mercenary Base.
Hendrix, the traitorous Ultor technician, led a group of miners to the Mercenary base. He informs Parker that the Mercenaries were setting up a bomb, enough to destroy all of Ultor's complexes, and destroying the Red Faction at the same time. Hendrix was killed by an explosive trap wired to a console. Parker hijacked an Aesir Fighter and flew through the Mercenary defenses. He soon after killed Masako herself, then defused the bomb. Soon after, the Earth Defense Force arrived, and took control of the facility. The Mercenaries were defeated, and the Red Faction claimed victory.
- Masako's name also exists in the Saints Row series. The team was led by Ultor Head of Security Dexter Jackson and was not a part of Ultor, but hired by Ultor too.
- Even though the Mercenaries are supposed to be "slaughtering" Guards, they don't do it inside the gameplay events. There are also no corpses of Guards anywhere.
- The Mercenary Grunt bares a striking resemblance to Commander Cobra from G.I. Joe.