sonic the hedgehog
He started his first game in 1991 in sonic the hedgehog for the sega mega drive. In 1992 sonic the hedgehog two was realesed it featured tails as well with sonic. In sonic the hedgehog 3 it once again featured sonic, tails, eggman and a new character knuckles. there were many other sonic games that time period of the 90s. There are many new sonic games to date such as sonic unleashed and sonic and the black night.
Sonic can do many transformations in the sonic series including
Wearhog sonic: Sonics latest transformation in which sonic turns into a werehog and has werehog powerd
Tails is a fox who has two tails he is sonic's best friend for more info see the tails page
Shadow is sonics arch rival he is mixed as he is good and bad sometimes he is undeafetable
In other media
Sonic has also appeared in sonic X