Nowadays Sonic has a huge supporting cast, but it's one of his earliest rivals which we remember best. Knuckles first appears in Sonic The Hedgehog 3 (all the way back in 1994) as an antagonist, but later that year they would team up in Sonic & Knuckles, cementing his position as Sonic's finest sidekick. Whilst Sonic provides the speed, Knuckles brings pure brawn and muscle. Able to break walls with a single swing of his giant fists, Knuckles is vastly more powerful than Sonic. He's also able to climb walls and glide, making him a much more versatile character than 'run-in-a-straight-line-until-I-get-stopped' Sonic. It's a shame that Knuckles' characteristics haven't been transformed into good Sonic levels (Sonic Adventure in particular has some horrible gameplay elements for Knuckles to deal with) but there's no doubt he's the better character. Let's not bring that horrifying Sonic Boom version of Knuckles into the discussion though.