Knuckles the Echidna (ナックルズ・ザ・エキドゥナ, Nakkurusu za Ekiduna?) is a video game character and a protagonist of the Sonic The Hedgehog game series, as well as some spin-off games and comics. His first appearance was Sonic The Hedgehog 3, released in 1994 to introduce a new rival for Sonic. Knuckles is a red 16-year-old anthropomorphic echidna, who is both physically powerful and highly resilient. He has a white crescent birthmark on his chest. He is both a friend and a rival to Sonic.
Knuckles' name is derived from the four knuckles, two on each hand, which are actually sharp spikes. According to official Sonic Team polls, Knuckles is the fourth most popular character in the series, following behind Tails, Shadow, and Sonic.