Naoto Ōshima is a Japanese national and former Sega employee who designed and created the characters of Sonic the Hedgehog and Dr. Eggman. However, Yuji Naka and Hirokazu Yasuhara often get the credit for his work on the Sonic series, because of their close association with the Sonic name. Ōshima gained renown at Sega's Sonic Team for creating characters and playing integral roles in the development of games like Phantasy Star, Sonic CD, Nights into Dreams, and Sonic Adventure.
After leaving Sonic Team, he formed an independent game company called Artoon. Since then he has stepped down from the position of president in the company and was replaced by Yutaka Sugano. There he went on to work on such games as Pinobee and Blinx: The Time Sweeper, and in 2004, the sequel to Blinx, Blinx 2: Masters of Time & Space. In 2010, Artoon was absorbed into AQ Interactive.
He is occasionally credited under the nickname "Big Island" (or "Bigisland"), which is a literal translation of his family name.
In 2010, he and other key members of Artoon left to form Arzest.