From Sonic Retro

Luigi MSOG.png
First seen: Mario Bros. (1983)
Species: Human
Gender: Male
Age: Unknown
Height: Unknown
Weight: Unknown
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Luigi (ルイージ, Ruīji) is a character in the Super Mario Bros. series, and is Mario's brother. He appears as a character in Mario & Sonic at the Olympic Games and Mario & Sonic at the Olympic Winter Games.

Due to being Mario's nearly identical younger brother, Luigi is often mistaken for Mario by many characters. This has proven to be somewhat of a running joke throughout the Mario series. Luigi's fame (or lack thereof) also plays a role in another major series running joke: he is often unnoticed by characters until they talk to him, and when he does, is often compared with his more famous and heroic brother.

Most often he is voiced by Charles Martinet, but in Super Mario Bros.: The Movie he is voiced and played by Columbian-American actor, John Leguizamo.