Mario is the main character in the series. He travels across the mushroom kingdom to save peach from the evil bowser. In his games he comes across some allies in his travels, such as his brother Luigi and Yoshi. However Mario doesn't just have allies to help he has special items called power ups he can find throughout his levels and games.
Power ups:
Luigi:
Luigi is Mario's brother. You can find Luigi in super guides in super mario bros games and in multiplayer games. But don't worry, Luigi does have his own games, he has Luigi's Mansion and Mario is Missing. Luigi is much taller than Mario and has a different kind of mustache, Luigi also can jump higher in some games like New Super Luigi U and Super Mario 3d World. In multiplayer games, Luigi is also able to use power ups like Mario
Yoshi:
Yoshi is Mario and Luigi's buddy that comes in to some levels but Yoshi can only be found in new Mario games like New Super Mario Bros. Yoshi has a flutter jump that can make Yoshi jump much longer and higher than Mario or Luigi in most games.
Power ups (Super Mario Galaxy 2):
Peach:
Peach is the Princess of the Mushroom Kingdom. She is a damsel-in-distress in most of the Mario. She loves the color pink since she does wear pink for her dress. She first appears in Super Mario Bros. but she does have her own game: Super Princess Peach. In this game she is the main character trying to save Mario and Luigi.
Toad:
Toads are the citizens of the Mushroom Kingdom. You can find them in places like, toad houses, ends of the castle in the first mario bros, and at Peach's castle as well.
Bowser:
Bowser is the king of the koopas. He is the one who kidnaps Princess Peach. To Mario, he is the bad guy and the final boss in almost every game in the franchise.