Emperor Ivo Robotnik, also known as Eggman, is a large human, the current Emperor of Mars, the kingpin of the Adeptus Mechanicus, and a very prevalent opponent of Earth. He heads the Egg Empire, the primary political/military authority on the planet of Mars. Though he is Mars' Emperor, and a member of the Sol Alliance, he is no friend of Earth.
Robotnik is one of the few human leaders to have ever caused harm to other humans and Earth. He bears many goals in common with the rogue human organization Cerberus, and they have even asked him for alliances in the past. However, Robotnik has turned them down every time, as he has little respect for Cerberus.
Around the year 2152, Emperor Robotnik had his Mechanicus Guild develop a machine that could allow for inter-dimensional travel. Through means yet unknown, this goal was accomplished, and Robotnik ordered a significant portion of his Empire's army across the subsequent dimensional gateway. This led to a massive invasion of the realm known as Mobius, where all manners of atrocities are committed to this day during the War for Freedom. However, when questioned by entities outside his Empire's inner circle, Emperor Robotnik denies everything, even the development of inter-dimensional gateways.