Classic Sonic is Sonic the Hedgehog's original appearance. He appears in 1991 and every Sonic game that he is in until Sonic Adventure. His sprites was used in Sonic X(Leapster) and his latest appearance is Sonic Generations.
Classic Sonic's look is exactly like Modern Sonic, but is shorter, fatter(fans' description), and have black eyes instead of green. Also, there is no yellow ring on his shoe. Due to Sonic's newest design, he is so far the only one who haves gloves.