Mario was born and raised in Italy along with his brother, Luigi. He went to trade school and became a plumber, which led to his many adventures. He is the Mushroom Kingdom's greatest defender.
Luigi accompanied his older brother Mario in his adventures as a plumber. He assists Mario in his many encounters with Bowser and his army. Along with Mario, Luigi is honored as a great protector of the Mushroom Kingdom.
Bowser had to work for everything he has, which includes his collection of massive castles. He is an advocate for the destruction of the Mushroom Kingdom, and does everything in his power to disrupt them.
Donkey Kong was raised in a small jungle full of explosive barrels and cannons. He spends his days spreading chaos in the Mushroom Kingdom by capturing Princess Peach.