We're talking major parts for Sonic, Tails, Knuckles, Tom ... and 1993 before being introduced in the games in 1993's Sonic CD, originally the flagship game of the Sega CD, itself a CD-ROM ...

Sonic CD followed Sonic trying to stop Doctor Robotnik ... arriving to cause trouble for the newly formed trio of heroes, Sonic, Tails, and Knuckles, as they adjust to their earthly lives.