Sonic Underground (French: Sonic Le Rebelle) is an animated television series co-produced by DIC Productions, L.P., Les Studios Tex S.A.R.L. and TF1. It is the third Sonic the Hedgehog animated series, and the last to be produced by DIC. It follows a main plot separate from all other Sonic the Hedgehog media, where Sonic has two siblings, Sonia and Manic, that are collectively part of a royal family who were forced to separate from their mother, Queen Aleena, upon Doctor Robotnik's takeover of Mobius due to a prophecy told by the Oracle of Delphius. Along the way, they encounter other resistance groups against Robotnik as well as powerful artifacts that could wreak havoc on the world, all the while searching for their long-lost mother Queen Aleena.
 The series first aired in France from January to May 1999 on TF1, and then premiered in the United Kingdom in May 1999 on ITV on the GMTV strand and finally in the United States in the syndicated children's block BKN Kids II from August to October 1999. It also aired on Kids' WB and the Sci-Fi Channel on weekday mornings starting October 1999, lasting until October 2000. The show ran only for one season consisting of forty episodes.
 There was a time when Robotropolis was beautiful. It was then a peaceful city known as "Mobotropolis". But just after my children were born, the evil Doctor Robotnik used his technology... to turn our world... into a place of terror. As the source of Robotnik's money, the aristocrats were left to play, while our people were roboticized... and became slaves. Our royal family was outlawed, a price placed on our heads. Then, the Oracle of Delphius revealed the prophecy to me. (Oracle: Some day, you will reunite with your children to become the Council of Four... and overthrow Robotnik. But there is a price, Your Highness.) For the prophecy to be fulfilled, I had to give up my babies. The show takes place in a separate canon and continuity than any other Sonic the Hedgehog media. Queen Aleena, the former ruler of Mobius, was overthrown by Dr. Robotnik and his bounty hunter lackeys Sleet and Dingo. Robotnik seized control of the planet and forced Queen Aleena into hiding. To preserve the dynasty, Queen Aleena separated her three children: Sonic, Manic, and Sonia after the Oracle of Delphius told her of a prophecy, proclaiming that one day, Queen Aleena would reunite with her children to form the "Council of Four," and overthrow Robotnik. Meanwhile, Dr. Robotnik did his best to set up an autocratic government, and legally turned anyone who stood against him into robots devoid of free will, and forced the nobles into paying large amounts of money to him as tribute.
 When Sonic, Manic, and Sonia grew up, the Oracle of Delphius revealed the prophecy to them. After that, Sonic, Manic, and Sonia decided to go on a quest, searching throughout Mobius for Queen Aleena. Dr. Robotnik, with the assistance of the Swat-Bots and his bounty hunters Sleet and Dingo, tries constantly to capture the royal hedgehogs and prevent the prophecy from being fulfilled.
 The Oracle of Delphius has assigned the three siblings powerful "medallions" that can change into musical instruments, and can also be used as weapons. Sonic's medallion is an electric guitar, Sonia's medallion is a keyboard that functions as a smoke machine, and Manic's medallion is a drumset that can be used as an "earth controller" with cymbals that can deflect laserfire. All of the medallions can be used as laser guns. The three use the amulets not only to fight Robotnik's forces but also as instruments for their underground rock band, "Sonic Underground."
 It is often claimed that the newly Sega of America CEO Shoichiro Irimajiri contacted DIC CEO Andy Heyward to make a new Sonic cartoon, which would help gain interest in buying their new console, the Dreamcast.[citation needed] Sonic Underground started production in early 1997, around the same time the development of both the Dreamcast and Sonic Adventure had started. The show bible was written as early as March 1997. The show was publicly announced as early as December 1997.
 When the show was in development, two episodes per week were produced, and the writers felt that they were not given enough time to "tie everything together" in the plot, being limited to a three-part "Origins" saga for coherency. DIC used cattle calls to generate episode plots. Periodically, about twenty unaffiliated writers were brought into the studios to learn about the established characters and brainstorm possible plots for episodes, after which about one or two would be selected. According to Mike Piccirillo, when he was writing songs for the show, there were no storyboards done yet, so he could only work off of the scripts, which often said what moral or lesson the song should be about in each episode. The show's animation was outsourced to the Taiwanese animation studio Hong Ying Animation with the storyboards and main title animation done in Madrid, Spain by Milimetros, S.A. (also responsible for the animation in the Saturday morning Sonic the Hedgehog cartoon and some of the storyboards in Adventures of Sonic the Hedgehog), pre-production services provided by Le Studio Ellipse, layout services by Arles Animation and video and audio post-production services by Les Studios de Saint-Ouen. According to Robby London, Sega of Japan had an active role in the approval process for Sonic Underground, going so far as to force DiC to reanimate the characters with five fingers instead of the usual four due to the Japanese association of four fingers with the yakuza.
 While it was once believed that 65 episodes were made of which only 40 aired, Ben Hurst, a main writer from Sonic the Hedgehog (dubbed SatAM by fans), who was also involved in Sonic Underground's production, stated in a chat at the Sonic Amateur Games Expo 2008 that only 40 were planned to be produced from the beginning.
 Sonic Underground first premiered in France on 6 January 1999 and aired on TF1 on the TF! Jeunesse block on Wednesdays and Sundays.
 The show made its English premiere in the United Kingdom on May 2, 1999, airing on ITV's GMTV strand, on the Disney-produced block Diggit, which was programmed by the show's distributor Buena Vista International Television and had also aired other programmes produced by DIC Entertainment at the time. ITV aired the first 18 episodes of the series on Sunday mornings before the series was removed from the Diggit schedule.
 In 2005, DIC pre-sold the series to GMTV, and so the series reran on ITV2 in 2005 as part of the GMTV2 Kids strand.
 By 2006, alongside the other Sonic cartoons, the series began to air on Pop, and by 2012, was airing on its sister channel Kix!
 In January 1999, it was announced that Bohbot Entertainment had acquired the North American broadcast rights to the series to air on their BKN syndicated strand. The series premiered in the country on August 30, 1999, on the company's then-new BKN Kids II on weekday mornings at 6:00 AM Central Time., and ran until  October 22, 1999.
 The series also aired on the Sci-Fi Channel which BKN also had a broadcast deal with at the time, however, the episodes that were supposed to air on Fridays were skipped because Double Dragon and later King Arthur and the Knights of Justice were airing instead, therefore only 32 of the 40 Sonic Underground episodes aired on that channel.
 In 2004, the show returned to syndicated television stations on weekends as part of the DIC Kids Network E/I strand. It, alongside fellow DIC series Mummies Alive! were the only two programs on the strand to not fulfill E/I requirements.
 On January 19, 2006, CBS announced a multi-year deal with DIC to broadcast some of their shows on the "CBS's Secret Saturday Morning Slumber Party" segment, including Sonic Underground, however, the block would not end up running the show in the end.
 In 2009, reruns of Sonic Underground aired on Firestone Communications' Sorpresa, a Hispanic children's station (Channel 850 on Time Warner Cable) in the United States, broadcasting the audio-dubbed Latin Spanish dub.
 Re-runs of the series aired on Disney XD starting June 11, 2012 and ending on December 14, 2012. This marked the second time a Sonic the Hedgehog cartoon has aired on a Disney-themed channel, with the first being Adventures of Sonic the Hedgehog on Toon Disney (the predecessor of Disney XD)  from 1998 to 2002.
 The series aired in Canada on Teletoon.
 In Australia, Sonic Underground premiered on The Seven Network during The Big Breakfast in 1999.
 The show was broadcast by KidsCo in regions the channel broadcast from.
 In the United States, Sterling Entertainment released a VHS/DVD titled "Dr. Robotnik's Revenge" in July 2003, containing three episodes, and a bonus Super Mario Bros. episode on the DVD release. It was re-released by NCircle Entertainment in March 2007 without the bonus Mario episode. The Sterling versions of the Adventures of Super Mario Bros. 3 "King Koopa Katastrophe" and The Legend of Zelda "Ganon's Evil Tower" DVDs also included 1 and 2 episodes respectively as DVD bonuses which the NCircle reissues of both releases excluded. Sterling Entertainment's VHS/DVD release of Sonic Christmas Blast also included 3 episodes (2 on the VHS).
 Shout! Factory and Vivendi Entertainment have released the complete series on DVD in Region 1 (NTSC) in two volume sets. Volume 1, simply entitled Sonic Underground, was released on December 18, 2007. It contains the first 20 episodes of the show on three discs, with disc three also including interviews with DIC's Robby London, Mike Piccirillo, an opening title animatic, and concept art. A bonus fourth disc is an audio CD containing eight songs from the series, including the opening theme. Sonic Underground: Volume 2 was released on 17 June 2008, featuring the remaining 20 episodes and another bonus audio CD featuring eight more songs from the series.
 From 2007 until 2010, NCircle Entertainment released several single-release DVDs containing four episodes each:
 NCircle also re-released Volumes 1 and 2 in 2013 and 2017, respectively. On July 25, 2023, they released the complete series as a four disc set.
 As of January 2018, Sonic Underground is available on the iTunes Store.
 In 2004, Anchor Bay UK obtained rights to distribute several DIC cartoons, including Sonic Underground on home video. The first two volumes were released on May 31, 2004 while the next two were released on August 16, 2004. There were plans for the remaining six volumes to be released separately, but they were instead released in a 10-DVD boxset in October 2004.
 In July 2005, Avenue Entertainment released two budget DVDs containing two episodes each.
 Delta Home Entertainment released the complete series again on DVD in June 2008 as a 4-disc set, with the fifth DVD containing the bonus features from the Shout! Factory DVD boxset. Delta Home Entertainment also released the four discs separately, with Disc 1 and 2 being released as "Beginnings" and "Who Do You Think You Are" in August 2008, and Discs 3 and 4 being released as "When in Rome" and "Country Crisis" in September 2008.
 Sonic Underground received mixed to negative reviews: it was criticized for its complex plot and large amount of differences from the games, although some critics have defined the music as catchy. David Cornelius of DVD Talk said, "While many Sonic fans did not take too well to all the changes, preferring the original 'Sonic' cartoon to this stranger, sometimes darker, sometimes sillier incarnation, the series did win a small but loyal cult following. I fall more on the side of disappointment - for all the cleverness that went into crafting an all-new backstory, the episodes themselves are uninspired - but acknowledge the simple fact that it scores well with its target audience." GamesRadar called the show as one of "the absolute worst Sonic moments", criticizing the extra characters and the complex plot. Patrick Lee of The A.V. Club panned the series, calling it one of the most artistic failures to ever end up on television and "the result of several unrelated ideas forcibly squashed into one project". Comedian Chris Hardwick commented on the show's theme song, composed by Mike Piccirillo, claiming that "that guy sounds like he's trying to win his exwife back." Susan Arendt of Wired said "The songs are actually kind of catchy in a Saturday morning cartoon kind of way, but the band thing still seems a bit out of place, especially when the instruments turn into weapons." Emily Ashby of Common Sense Media said "Sonic Underground has some good things to offer kids, but only if they're ready for the complexities of its story" criticizing its complex plot but complimenting its low violence and ability to entertain children.
 The Sonic the Hedgehog comic from Archie Comics featured a story in one of its special issues in which the Sonic Underground continuity was featured. According to the comics' plot, the reality in which Sonic Underground takes place is one of many parallel universes that share elements with Sonic's own. In the story, Sonic Prime—hailing from the main universe in the comic series—joins forces with his counterpart and siblings to stop Dr. Robotnik, who has managed to assemble a monstrous battle machine known as the Giant Borg. Robotnik obtained the pieces for this machine due to being mistaken for one of his own counterparts by Evil Sonic, an evil counterpart of Sonic's who later came to be known as Scourge the Hedgehog.
 The Sonic Universe spin-off comic was originally scheduled to feature an epilogue to the unfinished Sonic Underground for its 50th issue. However, for unknown reasons this was replaced with a story focusing on one of Sonic's long-running enemies, Metal Sonic. The Underground Epilogue was put on hold indefinitely, due to Sega not permitting the show be featured in the comics.