"Luigi (ルイージ, Ruīji) is a fictional character featured in video games and related media released by Nintendo. Created by prominent game designer Shigeru Miyamoto, Luigi is portrayed as the younger brother of Nintendo's mascot Mario, appearing in many games throughout the Mario series, frequently as a sidekick to his brother.

Luigi first appeared in the 1983 arcade game Mario Bros. as the character controlled by the second player, and retained this role in Super Mario Bros., Super Mario Bros. 3, Super Mario World, and other titles. The first game where he was available as a primary character was Super Mario Bros. 2. In more recent appearances, Luigi's role became increasingly restricted to spinoffs such as the Mario Party and Mario Kart series, though he has been featured in a starring role on two occasions; first in the 1991 educational game Mario is Missing and later in Luigi's Mansion for the Gamecube in 2001. In both of these games, he is called upon to act as the hero because Mario, the normal hero within the franchise, is in need of rescue.

Originally developed as palette swap of Mario with a green color scheme as opposed to red, Luigi has since developed a personality and style of his own. As his role in the Mario series progressed, Luigi evolved into a physically distinct character, taller and thinner than his brother. Although as kindhearted as Mario, Luigi is portrayed as timid and even a bit of a coward, especially in the presence of ghosts or when forced to do tasks that seemingly are impossible for him to accomplish."

Source: Wikipedia, "Luigi", available under the CC-BY-SA License.