Who is the bad guy in sonic?

The primary antagonist in the Sonic the Hedgehog franchise is Dr. Ivo Robotnik, also known as Eggman. He is a brilliant but evil scientist who seeks to conquer the world and often uses robotic creations to achieve his goals. His rivalry with Sonic, who embodies speed and freedom, drives many of the series' conflicts. Other villains occasionally appear, but Eggman remains the most iconic and enduring foe.