In Nintendo’s 1983 arcade game Mario Bros., Mario’s brother is named Luigi.
Mario Bros. introduced Luigi as Mario’s green-clad partner in a cooperative arcade adventure. The brothers work as plumbers in underground sewers, where they defeat creatures by striking the platforms beneath them and then kicking the stunned enemies away. Unlike later games, the original arcade title focuses on arena-like single-screen stages rather than side-scrolling platform levels.
Luigi’s appearance and role developed over time. In Mario Bros., he is essentially a second playable character, allowing two people to play cooperatively. His green clothing helped distinguish him from Mario, who traditionally wears red. Later Nintendo games gave Luigi a more defined personality and specialized starring roles, including Luigi’s Mansion.
A common mix-up is confusing Luigi with Toad, another major Mario character. Toad is a Mushroom Kingdom resident, while Luigi is Mario’s brother. Wario is Mario’s rival, and Yoshi is a dinosaur-like companion introduced in a later game.