Luigi, he of the green overalls, is Mario's younger, taller, thinner brother in the Super Mario Brothers universe. Sporting his own set of overalls, blue shirt, and green cap with an L on it, he typically he plays the role of "Player 2" and is merely a palette swapped version of Mario, but he has appeared as his own sprite (especially in recent years) and has even starred in a game of his own from time to time. Not only is a platformer side-scrolling game veteran, but he's also proven his worth as a sports fanatic, fighter, and adventurer. The basic rule of thumb is that wherever Mario is, Luigi isn't too far behind.

The green one's first appearance was in the arcade smash Mario Bros., but most Nintendo fans probably met him in the original Super Mario Brothers. Super Mario Brothers 2 was the first time that Luigi was his own distinct character and established that he can jump higher than his brother. However, by the time Super Mario Brothers 3 and Super Mario World came around he was back to playing second fiddle. Luigi continued to be a secondary character up until 1993's Mario is Missing, an edutainment title that simply reuses sprites from Super Mario World. Nonetheless, this game was the first time that Luigi took the lead role. This would be his last starring role until 2001's Luigi's Mansion. He took the spotlight again in 2003 in the Game Boy Advance RPG Mario and Luigi: Superstar Saga. When Mario and friends began to appear in spin-off games Luigi was along for the ride. He's a selectable character in all four Super Mario Kart games, plus he's taken up tennis (twice actually: once in Mario's Tennis and then again in Mario Tennis), golf (twice), and street fighting. In recent games Luigi's picked up an arch-nemesis of his own: Waluigi, a twisted, evil parody of himself to match Mario's own evil counterpart Wario. Luigi's also been romantically linked to Princess Daisy.

Despite his many appearances there have been some Mario games where he did not appear. He was absent for Super Mario 64 and Super Mario Sunshine, for example. In fact, many players refused to believe that he was not in Super Mario 64 and formed unofficial leagues to find him in the game. His only involvement in Super Mario RPG was in the instruction manual. All three Super Mario Land games also lacked his presence. Sometimes he is merely a background character, such as in Paper Mario and Super Mario Land 2: Yoshi's Island.

Nintendo has licensed out its Super Mario Brothers property many times, and most every time Luigi was included in these projects. He's been portrayed in live action by both Danny Wells (in The Super Mario Bros. Super Show) and John Leguizamo (in Super Mario Brothers: The Movie). He's been animated in The Super Mario Bros. Super Show, The Adventures of Super Mario Bros. 3, and Super Mario World. He even appeared in the various Super Mario Brothers comic books published by Valliant. There have also been a number of consumer products to bear his likeness, such as beach towels, juice glasses, fruit snacks, keychains, and many more products.

Luigi's been through a lot over the years and it's certain that we haven't seen the last of him. Many more adventures are undoubtedly ahead.

Luigi's Game Appearances


References:
Memory
http://www.classicgaming.com/tmk/
Did I miss a Luigi appearance? Let me know.