Sonic's human girlfriend

[Hypercat-Z]

Madonna was supposed to be a love interest for Sonic back when the original game was still in development. She was a blonde haired skinny human woman in a form-fitting red dress and was actually going to be Sonic's girlfriend. However, she was scrapped from the final game, along with other things that were to be in the story (like Sonic being in a rockband).
She was supposed to chase Sonic around like Amy Rose does in current games. She was first designed by Hirokazu Yasuhara, as a very attractive woman who would chase Sonic. She was later removed by Madeline Schroeder, her reason for removing Madonna was that she wanted to "soften" Sonic for children and foreign countries, because she thought it was too "Japanese". Madonna can also be considered the equivalent of Pauline in the original Mario game, Donkey Kong.

http://sonic.wikia.com/wiki/Madonna