Metal Sonic - Stronger, faster, you name it. Metal Sonic has Sonic beat in everything. First appearance in Sonic CD. According to the Sonic Anime storyline, Metal Sonic was created using Sonic's life data, thus making he and Sonic "twins". This also allows Metal to predict Sonic's moves making him virtually untouchable.

Silver Sonic - The prototype to Metal Sonic. Silver Sonic appeared in Sonic 2. Like Metal Sonic, Silver Sonic was better than Sonic in every possible aspect.

Metal Knuckles - A Knuckles-like robot that was first used in Sonic R. It has all of Knuckles' abilities. Later, Eggman improved the Metal Knuckles model in Sonic Advance and sent it to thwart Sonic and company on Angel Island.

Tails Doll - Rather than having a "Metal Tails", Dr. Eggman made a doll-like robot with Tails' abilities. It's very freaky.

E-102y - The second in Eggman's E-100 model series, E-102 codenamed Gamma, was one of Eggman's best Badniks ever; however, on an assignment to retrieve a bird carrying a Chaos Emerald, Amy Rose taught him to experience feelings. This completely through Eggman's plan of course and led to the destruction of the other E-100's.

Egg Robo - The Egg Robo piloted Eggman's machines, in Sonic and Knuckles. It was very powerful but met with an unfortunate defeat...

Zero - Eggman's search and destroy robot sent to capture Birdie, a Flicky who carried a Chaos Emerald. Amy Rose befriended the bird, as Zero pursued her, attempting to capture it. At the end of Sonic Adventure, Amy turned Zero into scrap metal with her Piko Piko Hammer.

Dr. Eggman - He is responsible for creating Metal and the other badniks. So he deserves a bit a recognition. Dr. Eggman has appeared as the main villian in literally every Sonic game; whereas, Sonic himself did not appear in two of them. A genius with an extremely high IQ of 300, Dr. Eggman should easily be able to defeat Sonic and his friends.