The "Sonic" franchise is known for its large cast of characters; "Sonic the Fighters" (1996) producer Yu Suzuki joked that anyone who makes a "Sonic" game has the duty to create new characters. The first game introduced Sonic, a blue hedgehog who can run at incredible speeds, and Doctor Eggman, a rotund mad scientist. During the Genesis and Saturn eras, Eggman was referred to as Doctor Ivo Robotnik in Western territories. Sega of America's Dean Sitton made the change without consulting the Japanese developers, who did not want a single character to have two different names. Since "Sonic Adventure", the character has been referred to as Eggman in all territories, although the Robotnik name is still acknowledged.