Mr. L

"Have at you!"

- Mr. L's catchphrase. "L-ater."

- Another catchphrase of Mr. L.

Mr. L is a major antagonist in Super Paper Mario. He is the evil alter-ego of Luigi and serves as the boss of Chapter 4 and Chapter 6. He was originally Luigi, but he later got brainwashed by Nastasia and was told to defeat Mario and his friends once and for all. Mr. L also has a robot that he calls Brobot, because he has a strong, brotherly bond with it.

Later in Super Paper Mario, after being defeated by the heroes twice, Dimentio kills Mr. L who then reappears as his normal self (Luigi) in the Underwhere. Luigi was soon reunited with Mario again and joins him to help his friends out.

He also technically serves as the final boss, as Dimentio brainwashes Luigi during the final battle, then fuses with him and the Chaos Heart, becoming Super Dimentio. However, Super Dimentio is defeated, which freed Luigi and returned him to normal again.

Personality
Mr. L can, from different points of view, be seen as both an upgrade and downgrade of Luigi. Unlike Luigi, he is very brave and confident of himself. He also seems very smart, seeing as he built Brobot all by himself. However, Mr. L has too much confidence, resulting in an egotistical behavior with many flashy poses. And all of Luigi's kindness and humbleness is gone. He also uses any positive attributes he gained from being brainwashed for evil deeds, which the real Luigi would never do.

Trivia

 * In Super Smash Brothers Brawl, he is mentioned in Paper Luigi's trophy, but as Mister L instead.
 * His stats: Max HP is 40, Attack is 3 and Defense is 0.
 * In the Flopside Pit of a Hundred Trials, Shadoo copies all of the game's main four heroes. However, when he copies Luigi, he actually has Mr. L's silhouette instead of Luigi's.
 * Throughout the game, Mr. L is treated as an outsider by most of the minions, but Dimentio takes special interest in him, aware of his power and manipulating him to serve his own evil plans.