Badniks are robots produced by Dr. Eggman. They are typically mass-produced, and are often used to carry out assaults against Sonic and his allies. Badniks are commonly powered by flickies, chaos drives, or rings, though some models have unique power sources or no apparent power source at all.

Badniks tend to have quite artistic designs. They can resemble common animals, insects, plants, other kinds of machinery, or even Eggman himself. Characters like Metal Sonic, Belle the Tinkerer, and Heavy are considered badniks even though they are not mass-produced and display higher intelligence.