Mario is the main character of the series. He is an Italian-American superhero, and was originally referred to as Jumpman in Donkey Kong. In most of the Mario spin-offs, he is the most average character, and is a good choice for starters.
Luigi is Mario's slightly taller brother, who wears green overalls. His abilities are usually the same as Mario's, but in some games Luigi can jump higher. Luigi is usually the sidekick, but was the hero in a few games such as Luigi's Mansion.
Princess Peach: Princess Peach is the Princess of the Mushroom Kingdom. Mario often saves her from Bowser.
Yoshi: Yoshi is a dinosaur that Mario rides in some games. He appeared in his own game, Yoshi's Island.
Toad: Toad is a mushroom-shaped creature who appears in many Mario series games. He is just one of many toads. These creatures first appeared in Super Mario Bros., where they were called Mushroom Retainers.