- Knuckles the Echidna, Shadow the Hedgehog, Blaze the Cat and Metal Sonic are probably the most stand out examples among the fanbase.
- Knuckles was Sonic's first true rival in the series, and people quickly latched onto to him for being a no-nonsense fighter with a Hidden Heart of Gold. As such, let's just say his later Flanderization was arguably one of the first controversial things that happened.
- Shadow quickly took the spot as Sonic's rival after Knuckles became much friendlier to Sonic, and his first appearance in Sonic Adventure 2 was essentially his high point, especially due to his Heroic Sacrifice. Heck, he was so popular that they brought him back in Sonic Heroes and gave him his own game. Opinions about him afterward vary for lack of a better term, but he still remains one of the more popular side-characters.
- Blaze's powers and appearance as a Defrosting Ice Queen with Character Development won her several fans, which only increased as she proved to be badass enough to fight Sonic on even footing during her debut game series and gaining her own Super Mode, something no other female character can claim to. The fact that said games are often cited as good only improves her standing, and she's generally considered to be among the least annoying of Sonic's friends of the Modern area.
- Metal is especially notable, because aside from Sonic CD, the character made no appearances in the major classic games,note being delegated to more obscure titles like Sonic Triple Trouble, Sonic the Fighters, Knuckles Chaotix and Sonic R, and mere cameos or non-canon appearances in the Sonic Adventure series. After his surprise comeback in Sonic Heroes, he was permanently cemented as a significant recurring foe in the series.
- Fang the Sniper (known as Nack the Weasel in the U.S.) was a recurring character in the Sonic franchise between the years of 1994 and 1998 and has many fans who want him to make an appearance in anything. Some of these fans got their wish when he cameoed on a wanted poster in Sonic Generations.
- All of the Chaotix are this, especially after Sonic Heroes revamped them into a trio of screwball, Crazy Awesome detectives. Espio especially. After all, he is a no-nonsense ninja and the Only Sane Man of the trio.
- Though they are controversial characters among the fanbase due to debuting in the infamous Sonic the Hedgehog (2006), Silver the Hedgehog and Mephiles the Dark have their share of fans. Silver, after his boss fight in Sonic Generations proved to be actually fun and also due to the Archie comics featuring him as a major character. Mephiles who, while his plans are so ridiculously complex that they should not work, is actually considered a pretty cool villain. This could be attributed to actually killing Sonic.
- E-123 Omega, especially when he became an Expy of HK-47 (see below).
- There's also Jet the Hawk and the Babylon Rogues who have a sizable fanbase.
- E-102 Gamma, extraordinaire, is notable as one of the few faces in this series not to attract bile from the fanbase. His Heroic Sacrifice (which stuck, not counting E-102r "Chaos" Gamma in Battle), his surprising amount of Character Development given his screentime, and the nature of his existence in general most likely helped.
- Tikal and Shade, the female echidnas who each have a pretty big fanbase considering how little they've been in the games. Tikal actually managed to defeat Dr. Eggman in Sonic Wiki's Character Tournament.
- Orbot (aka "Ergo") from Sonic Unleashed. His Scratch and Grounder-esque dynamic with Cubot in Colors further cements this.
- In another corner of the fandom, a great deal of prominence has been given to Honey the Cat, an extraordinarily detailed character who was Dummied Out of Sonic the Fighters. This may have motivated Sega's decision to promote her to playable in the 2012 'Xbox Live Arcade & Play Station Network Updated Re-release.
- Tiara has her fair share of fame despite never being properly released. Tiara's game (Sonic X-Treme) was infamously canceled.
- In addition you'll often find a strong fanbase of particular alternate media characters, many of which urging for them to appear in the games canon. Princess Sally Acorn has perhaps one of the most notable fanbases even compared to some games characters (even if it extends to Base-Breaking Character status) with Cosmo and Bunnie Rabbot also worth special mentioning.
- Among the villains and bosses, Perfect Chaos has a large fandom due to being a titanic water god of destruction with an awesome design and roar and a wooby backstory. Dark Gaia as well, though not to the same extent. The Egg Viper, final boss of Sonic's story in Adventure, is widely considered one of the best Eggman mechas in the franchise, along with Death Egg Robot and Big Arm.
Ensemble Darkhorse / Sonic the Hedgehog
Due to the very nature of this series' fans, Sonic the Hedgehog has many characters that can be considered Ensemble Darkhorse by different sorts of fans.