Mecha Robot Army (メカロボット軍団 Meka Robotto Gundan), or known as Robot Monster Army (ロボット怪獣軍団 Robotto Kaijū Gundan) were an army of past Ultra Kaiju robots that appeared in Ultraman Zero Gaiden: Killer the Beatstar. They were manufactured by Beatstar to aid him in the genocide against all life forms. All of the machines serving this battalion had their names with the (BS) initials to indicate their manufacturer and master.
Ultraman Zero Gaiden: Killer the Beatstar
The Mecha Robot Army was assembled by Beatstar within his Beatstar Celestial Sphere (ビートスター天球 Bītosutā Tenkyū) after analyzing various robotic armies used by past alien invaders. When the Ultimate Force Zero, Hyuga and Rei infiltrated the sphere, his Gomora fought a Beta model Legionoid, with Ultraman Zero against King Joe, Glen Fire against Ace Killer and Mirror Knight against Inpelaizer.
After cleansing Jean-Bot from Beatstar's viruses and redeeming Jean-Killer, the group first destroyed the Legionoid armies that surround them and arrived on the hemispherical artificial moon. The rest of the team left to fight the King Joe and Inpelaizer armies while Zero and Jean-Killer stormed the Beatstar Tower and defeated Beatstar, thus stopping his genocide against the organic life forms. Beatstar's defeat resulted with the destruction of his sphere and its contents, including his assembled Mecha Robot Army.
- Out of all four re-manufactured robots, Ace Killer is the only one who was not given a mass-production army.
- Despite their purpose as Beatstar's invasion soldiers, the robots were never used outside the Beatstar Celestial Sphere, since the artificial planet by itself was enough to destroy planets in a single collision. Their role on the planet was more or less for security purposes to eliminate trespassers.