Sonic the Hedgehog

Sonic's appearance varies greatly depending on the medium and the style in which he is drawn. In the video games, Sonic's original design by Oshima was short and round, with short quills, a round body, and no visible irises. Artwork featuring this design and drawn by Akira Watanabe was displayed on the package artwork for Sonic the Hedgehog, and most subsequent Sonic video games featured similar designs.

The original concepts gave Sonic fangs put him in a band with a human girlfriend named Madonna. However, a team from Sega of America, led by Madeline Schroeder, who calls herself "Sonic's mother", "softened" the character up for an American audience by removing those elements. This sparked a heated issue with Sonic Team. Naka later admitted that it was probably for the best.

Sonic was created without the ability to swim because of a mistaken assumption by Yuji Naka that all hedgehogs could not do so. A group of fifteen people started working on the first Sonic the Hedgehog game, and renamed themselves Sonic Team. The game's soundtrack was composed by Masato Nakamura of the band Dreams Come True. Sega sponsored the group's "Wonder 3" tour, painting Sonic on the tour bus, distributing pamphlets advertising the game, and having footage of the game broadcast above stage prior to its release.

Eventually, Naoto Ōshima's spiky teal hedgehog, initially codenamed "Mr. Needlemouse,"was chosen as the new mascot. Sonic's blue pigmentation was chosen to match Sega's cobalt blue logo, and his shoes were a concept evolved from a design inspired by Michael Jackson's boots with the addition of the color red, which was inspired by both Santa Claus and the contrast of those colours on Jackson's Bad; his personality was based on Bill Clinton's "Get it done" attitude.

Sega wanted a game capable of competing with Nintendo's Mario and a character to replace Alex Kidd as the company's mascot. Several character designs were submitted by its AM8 research and development department, including an armadillo (who later developed into Mighty the Armadillo), a dog, a Theodore Roosevelt look-alike in pajamas (who would later be the basis of Dr. Robotnik/Eggman's design), and a rabbit (who would use its extendible ears to collect objects, an aspect later incorporated in Ristar).