Luigi is the twin brother of Mario. Also another one of the top Mushroom Kingdom. He is very friendly also he's very scared of boos and ghost. However, he overcomes his fears and acts like a hero when necessary. He has a crush on Princess Daisy,Some of their team names from the Mario Party series include "Steady Sweeties," "Tango Tanglers," and "Shy Sidekicks." Also, in [[Mario Superstar Baseball] and [[Mario Super Sluggers], Luigi and Daisy are "buddy players," and they share very good chemistry. He is a playable character in all of his appearances such as Mario Party 7, Mario Kart: Double Dash!! and [Mario and Sonic at the Olympic games]].

Interestingly enough, Luigi is the only character to ever see a Shy Guy without a mask, becuase he won a mansion in a contest he hadn't even entered. Luigi called Mario and asked him to visit the mansion. Mario got to the mansion first. When Luigi arrived, Mario was nowhere to be found and ghosts haunted the mansion. Luigi met Professor E. Gadd and received the Poltergust 3000, a vacuum that allowed him to capture ghosts.

His latest appearance was in New Super Mario Bros. Wii. Where, once again, Princess Peach was kidnapped and had to be saved by Mario. This time, she had been kidnapped by Bowser Jr., Bowser's son. Mario went to save the princess with a little help from Luigi.