Back to the Future/Sonic

AoStH/SatAM/Underground series

 * Marty McFly as Sonic
 * Einstein as Tails
 * Doc Emmet Brown as Knuckles
 * Jennifer Parker as Sally
 * George McFly as Uncle Chuck
 * Lorraine McFly as Bunnie
 * Biff as Dr. Robotnik
 * and more

Sonic X

 * Marty McFly as Sonic
 * Einstein as Tails
 * Doc Emmet Brown as Knuckles
 * Jennifer Parker as Amy Rose
 * George McFly as Vector
 * Lorraine McFly as Vanilla
 * Biff as Dr. Eggman
 * and more