Dr. Ivo Czernin Robotnik Jr. is one of the secondary antagonists in the Sonic the Hedgehog series, the other being Metal Sonic. He is an American scientist, lawyer and politician. He is a member of the prominent Robotnik family and the eldest son of Ivo "Eggman" Robotnik and Joan Robotnik, the junior United States Senator from Massachusetts, and the arch-nemesis of Miles "Tails" Prower. He is the older brother of U.S. Senator Joseph Robotnik. He is a member of the Democratic Party.
Ivo Jr. is 37 years old, and 6'0", which is the same height as his younger brother Joe, and nearly the same height as his father. He has a medium build and is more slim than his father. Having lost his limbs to an IED in Afghanistan during his time of service in the U.S. Navy SEALs, he has robotic limbs that were made for him by his 1st cousin, once removed, Gerald Robotnik III, and upgraded by his father, Dr. Eggman. The upgrades that Ivo Jr.'s father made to his prosthetics gave Ivo Jr. the ability to jump higher, and increased his strength. He has brown hair that is parted on the left side of his head and slicked back, and piercing blue eyes. His usual outfit is a black suit, an American flag lapel pin, a white dress shirt, dark blue necktie, and black and white dress shoes.
Ivo Jr. is a charismatic and smooth-talking politician. He is shown to be a dutiful husband and father. However, he is also very ambitious, having been groomed by his father, Eggman, to become President of the United States, and he became evil, corrupt, and villainous when he joined his father to help him conquer the world. Unlike his father however, Ivo Jr. is more mild-tempered and is more kinder to his henchmen. Since Ivo Jr. is from Boston, he speaks in a thick Boston accent like his younger siblings. He is a brave, courageous, tough, and audacious individual, as shown during his time in the U.S. Navy SEALs. He does not want his children to follow him on the path to villainy, which explains why he allows them to help Sonic and his friends.
- Ivo Robotnik, Jr. is based on and is modeled after Joseph P. Kennedy, Jr.
- As a member of both the House Intelligence Committee and the Armed Services Committee, Ivo Jr. sits on the same House committees as his brother Joe.