Luigi is Mario's younger, but taller, twin brother.
Luigi has assisted and fought alongside his brother on many occasions. Throughout his life, he has lived in Mario's shadow, developing both cowardly and heroic tendencies. Mario Bros. marks his first appearance in a Super Mario arcade game. Originally a color swap of Mario, Luigi was created to facilitate a second player option. Since the two player mode was dropped from most Super Mario games beginning with Super Mario Land, Luigi had gained his own identity and personality.