Androids was a term used to describe the robotic creations of Dr. Gero. In the series, the Z Fighters have faced various androids, androids 8, and later 16, 17, 18, 19, 20 and Cell.
Dragonball Online introduces 2 new androids, based on the androids 8 and 19. Commander Red, of the Red Ribbon Army became android 9. Another series of Androids are the Bio-Androids, which are based off the android Cell.