Dr. Eggman

Dr. Eggman, also known by his real name Dr. Ivo Robotnik, is a persistent enemy and the arch nemesis of Sonic the Hedgehog, much in the same manner as Bowser opposes Mario.

Mario & Sonic at the Olympic Games
Dr. Eggman, as well as several other Sonic the Hedgehog series characters, appears in the Olympic crossover game Mario & Sonic at the Olympic Games. He is a Skill player, despite his rather large size, and he's also unusually fast. However, Dr. Eggman is lacking in power, and his stamina isn't that strong either.

Mario & Sonic at the Olympic Winter Games
Eggman appears as a character in Mario & Sonic at the Olympic Winter Games, and appeared in the first trailer for the game along with Sonic, Mario, and Wario.

In the DS version of the game, in the Adventure Tour mode, he is one of two main antagonists, along with Bowser. He and Bowser try to stop the 2010 Olympic Winter Games by capturing all the Snow Spirits.

Profile
''Although the devious Dr. Eggman has great Skill-based abilities, he also is quite powerful. His huge, lumbering frame doesn't give the impression that he would be good at gymnastics, but believe it or not, he can handle the trampoline and vault quite well.''

''Super Smash Bros. Brawl
Dr. Eggman makes a cameo appearance as a collectable trophy in Super Smash Bros Brawl, which is obtained by collecting over 500 stickers. He also appears on a sticker which increases a character's launch resistance by 39 points.

Trivia

 * Dr. Eggman has a bulbous pink nose similar to Wario, Waluigi, Dr. Crygor, Jimmy T., Jimmy P., and Booster.
 * Dr. Eggman, along with Miles "Tails" Prower and Amy Rose, are the only characters in the Sonic series to have formal names.
 * Dr. Eggman and Bowser are similar in several ways:
 * They're both portrayed as major villains.
 * They both kidnapped a female character at least once.
 * They both had to team up with their arch-nemesis at one point to defeat a bigger threat.
 * They both have a grudging respect for their arch-nemesis.
 * They both have similar transportation (Bowser's Koopa Clown Car and Dr. Eggman's Egg Mobile).