Dr. Eggman

 is the main Villian in the Sonic the Hedgehog series of games. He is Sonic the Hedgehog's arch enemy.

Chaos
In Sonic Adventure found Chaos 0 and went to obtain the [Chaos Emeralds]] to power up Chaos so that he could destroy Station Square. Eventually,He found all seven Chaos Emeralds and gave them to Chaos turning him into Perfect Chaos

The ARK
In Sonic Adventure 2 He entered a top secret goverment base to find Shadow the Hedgehog. Shadow the Hedgehog told him of a space station,the ARK, that had a weapon,called the Eclipse Cannon,which was so powerful that it could destroy stars.The only problem is that it needed power from the Chaos Emeralds. Later, He got them and put them in it, but he noticed that he had done something wrong and helped Sonic deactivate the cannon.

Trivia

 * is often called Dr.Eggman by Sonic.
 * He apparently likes Chaos as he has a Chao Garden on his ship,the Egg Carrier and has a room full of them in his castle.
 * He has an IQ over 300