List of Luigi sightings in New Super Luigi U

In every course of New Super Luigi U is a picture of Luigi hidden, whether it be a sprite, a image in a wall, or otherwise.

3-1 Huckit Beach Resort

 * Above the second Star Coin, an 8-bit Luigi is swimming.

3-2 Urchin Reef Romp

 * Shortly after the third Star Coin, an 8-bit Luigi will appear.

3-Tower Shish-Kebab Tower

 * To the northwest of the second Star Coin, an 8-bit Luigi is hidden in the wall.

3-Ghost House Haunted Cargo Hold

 * When the player goes down the first set of pipes, they must jump in the water and swim left to find a swimming 8-bit Luigi hidden in the wall.

3-3 Waterspout Sprint

 * Below the Red Ring is an 8-bit Luigi.

3-4 The Great Geysers

 * Behind the course's starting point is a series of large blocks with lines made to resemble Luigi's head.

3-5 Dragoneel Depths

 * Before going up the pipe leading to the Goal Pole, an 8-bit Luigi is seen swimming.

3-Castle Larry's Trigger-Happy Castle
After hitting the P-Switch and clearing the coins at the top of the pipe, you can see a 8-bit swimming Luigi.

3-Secret Beanstalk Jungle
Just before entering the last pipe, head over to the right to see a 8-bit Luigi.

4-2 Cooligan Shrooms

 * Near the the 3rd Star Coin, there is an 8-bit Luigi sprite hanging on a mushroom.

4-3 Fire and Ice

 * In the area with the first Star Coin, there is an ice sculpture of Luigi.

5-2 Dancing Blocks, Poison Swamp

 * A Luigi sprite can be seen clinging to the top of the secret flagpole.

5-Ghost House Boo's Favorite Haunt

 * There is a portrait of Luigi to the right of the door leading to the secret exit.

6-1 Mount Fuzzy

 * Above the 1st Star Coin is a secret area with an 8-bit Luigi.

6-Tower Smashing-Stone Tower

 * In the area where the second Star Coin is.

6-5 Rising Piranhas

 * There is a large Luigi-shaped hole in the rock wall just before the Super Piranha Plant next to the secret exit in the ceiling.

7-Ghost House Vanishing Ghost House

 * If the player takes the secret exit route, they will see a picture of King Boo and Luigi, which references their artwork from Luigi's Mansion: Dark Moon.

7-5 Flame Chomp Ferris Wheel

 * A cloud resembling Luigi can be seen in the background.

8-1 Magma Moat

 * There is a statue of Luigi taking off his hat at the secret flagpole.

9-6 Fire Bar Sprint

 * Break the last set of blocks near the flag pole to find a crouching 8-bit Luigi.