Here are all the evil armies in the Gradius series.
Bacterian is the most recurring force in the Gradius Series. It is a semi hive minded empire of brain-like creatures that came from a living planet of the same name. It has been also headed by Gofer, O.V.U.M., an evil force from the Dark Nebula, Dr. Venom, an ally of Bacterian and the Gofer Sisters.
Salamander is a special force sent by Bacterian to transform Latis into an organic fortress.
Dark Force is the most brutal Bacterian force in the Gradius series.
The Lars Empire is a human empire that has obtained Bacterian and Gradian technology in a time the Gradian Empire and Bacterian no longer exist.
The main villain of Xexex.