Mr. L, A.K.A The Green Thunder, is Luigi's evil alter-ego after he was brainwashed by Count Bleck's assistant, Nastasia, in the game Super Paper Mario. He has built a giant robot he calls "Brobot" (It looks like him) which he uses to fight Mario and his friends. He made a second version of Brobot called Brobot L-Type that has arms and legs. He appears as a Paper boss in Mario and Luigi: Paper Combine.
Mr. L is a playable character in Star Hedgehog: Adventurous Team. He is the highest jumper and can use the Charge Jump from Super Mario Bros 2. He can also use the different powerups:
- Fire Flower: Fire Mr. L
- Super Leaf: Kitsune Mr. L
- Hammer suit: Hammer Bro Mr. L
- Frog suit: Frog Mr. L
- Propeller Mushroom: Propeller Mr. L
- Blue Shell: Shell Mr. L
- Chaos Emeralds: White Kitsune Mr. L
Mr. L is a boss in Bowser's Life Story, from world 3, the Paper World.