There are 17 playable characters in the base version of Mario Kart 7.
The roster consists of 16 standard Mario characters plus a playable Mii character. Newcomers include Metal Mario, Lakitu, Wiggler, and Honey Queen. Returning racers include Mario, Luigi, Peach, Yoshi, Bowser, Donkey Kong, Toad, Koopa Troopa, Daisy, Wario, Rosalina, and Shy Guy.
Eight racers are available immediately, while most of the remaining characters are unlocked by progressing through Grand Prix cups. The Mii becomes playable separately after meeting its unlock requirement. This is why some lists report 16 characters: they count only the named Mario-series racers and exclude the Mii option.
Mario Kart 7 was released for Nintendo 3DS in 2011. Its roster was smaller than Mario Kart Wii's, but the game introduced several major gameplay features, including underwater driving, hang-gliding sections, and customizable karts.