Sonic the Hedgehog had taken hold of pop culture by the mid-1990s, serving as a solidly “cool” video game mascot in addition to being a formidable rival to Nintendo’s Mario. But Sonic got his own in-series rival with the arrival of Knuckles the Echidna, who debuted in Sonic the Hedgehog 3 in February 1994.
Knuckles is a red echidna with spiked hands, which he uses most often for combat. He is the guardian of the Master Emerald, a massive stone that has control over the franchise’s seven other Chaos Emeralds. During Sega’s initial work on Sonic 3, the team wanted to create a character that would be a formidable rival to Sonic – Knuckles was chosen from among dozens of other designs due to his intimidation factor.
In the context of Sonic 3, Knuckles is an enemy seen a few times throughout the story, as Dr. Eggman has tricked him into fighting against Sonic and Tails by telling him that Sonic is after the Master Emerald. Throughout his history, Knuckles has been proven to be gullible like that several times. Though he usually keeps a calm and collected, almost cold demeanor, he also has a tendency to butt heads with other characters in the series (most often Sonic).
After Sonic 3 proved to be a success, Sega released Sonic & Knuckles, making Knuckles playable for the first time. Sonic & Knuckles was actually developed simultaneously with Sonic 3, but the technological limitations of the time forced Sega to split the project into two titles. The cartridge for Sonic & Knuckles was notable for including “Lock-on Technology” which allowed for gamers to connect it to either Sonic 2 or Sonic 3, which combines elements from those games.
Knuckles has since gone on to star in his own titles (Knuckles Chaotix) and has appeared in dozens of other Sonic franchise titles as one of the main playable characters. He has also appeared in the Sonic cartoons and comic books. Knuckles is one of the most popular characters in the Sonic franchise at large, thanks largely in part to a slick design combined with abilities gleaned from his spiked gloves that no other character shares.