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.

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.

9-1 ''Spine Coaster Connections

 * Shortly after the first Fuzzy, an 8-bit Luigi will appear in the grassy land above.

9-2 P Switch Peril

 * Break the blocks above the fourth P Switch to uncover a hidden 8-bit Luigi.

9-3 Star Coin Deep Dive

 * Break the Brick Blocks below the Red Ring to uncover a hidden swimming 8-bit Luigi.

9-4 Hammerswing Hangout

 * Shortly after passing the Green Ring, look out for an 8-bit Luigi on the right.

9-5 Under Construction

 * When the player goes up the level's Beanstalk, the player can climb up and down on a 16-bit Luigi.

9-6 Fire Bar Sprint

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

9-7 Cloudy Capers

 * When traveling through the last set of Fuzzies, use a Fireball to hit the second to last Fuzzy on the bottom right to reveal an 8-bit Luigi.

9-8 Impossible Pendulums

 * When you've gotten to the last Ball 'n' Chain, head down to the bottom right corner to find an 8-bit Luigi in a secret area.

9-9 Flying Squirrel Ovation

 * Near the bottom of the Gliding Portion, a giant 8-bit Luigi appears.
 * At the end of the level, there's a big sign saying 'THANK YOU' with a Luigi cutout on it. You can put your Mii's face through the hole.