The Zelos Force are recurring enemies in the Gradius series, first appearing as the final boss of Salamander.
The Zelos are giant creatures created by the Bacterians to serve as planet-modifying systems (implying that they are part mechanical). They take on the shape of a large red eye, though they are able to mutate into other forms and even pilot other Bacterian machinations. Though they were initially defenseless, they later gained the ability to shoot laser beams and homing bolts.
It first appeared controlling the Salamander Planetoid, which led the Salamander forces in their attack against Planet Latis. Upon it's destruction, the planetoid self-destructs. In the MSX version of Salamander, Dr. Venom is reincarnated inside of Zelos, summoning the powerful Metal Slave to fight the heroes. After the ultimate demise of the Bacterion Empire, the Zelos Force becomes free, living in the wild.