Bacterian is a cell that uses his Dark Force powers and his multiplication abilities to create fleets of organic monsters and mechanical ships so that he can conquer the universe. His place of birth is unknown though he said that he was born from the greediness of mankind.
Bacterian started the first Bacterian War and sent a fleet to destroy planet Gradius. The fleet was destroyed by a ship named Vic Viper. He sent a second fleet named Salamander and sent another fleet headed by a giant head named Gofer. In the Third Bacterian War, this time, Vic Viper reached the Bacterian's Homeworld and destroyed Bacterian. 400 years later, a piece of Bacterian landed on a planet and transformed it into a fortress. That piece was destroyed by Vic Viper.