Sonic Underground (Sonic le Rebelle in French) is a French/American animated television series that follows the adventures of Sonic the Hedgehog and his siblings, pink-hued Sonia, and green-hued Manic. Sonic Underground bears little relation to the often complex Sonic universe (including previous animated series, as well as Sonic comics and games), and shares only three established characters.
Over two seasons, forty episodes aired. Ben Hurst, a notable writer from the Sonic the Hedgehog television show, who was also involved in Sonic Underground's production, stated in a SAGE chat that only forty were produced. According to Hong Ying, the animation studio who animated Sonic Underground list forty episodes which are the complete series.
Sonic Underground takes place on Mobius, similar to the Sonic the Hedgehog TV series, but with notable differences. Elements that are not included in Sonic Underground but were present in Sonic the Hedgehog include Snively, Power Rings, Knothole Village, and the Freedom Fighters. Though the Freedom Fighters were included, many of the characters in the Freedom Fighter group that were in Sonic the Hedgehog are completely left out (including Tails). Another difference with the Freedom Fighter group is that Freedom Fighters do not remain in one Knothole-like refuge but instead travel around Mobius to battle Robotnik's forces on a global scale; and that Robotnik has left most of the Mobian people de-roboticized, leaving multiple cities, a poor underclass and an aristocracy for the heroes to interact with.
Another notable difference is Robotnik's choice of law enforcement in the two continuities. While both versions featured Swatbots as Robotnik's grunt troops, their designs differed by a mile and more. The SatAM Swatbots also all looked identical, while the Underground Swatbots had two different head designs.
Jaleel White provided the speaking voices for all three siblings (whereas they are voiced by different voice actors when they are singing). The main theme was composed by Robbie London and Mike Piccirillo. The musical underscore was composed by Jean-Michel Guirao and Mike Piccirillo. The series featured forty songs spread over the series as featured music videos. Each of these songs was composed by Mike Piccirillo.