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.

Acorn Plains
1-1 Waddlewing Warning! On top of the New Super Luigi U sign in the beginning of the course is an 8-bit sprite of Luigi standing.

1-2 Crooked Cavern Right before the normal exit is an 8-bit Luigi sprite under the stairs of Brick Blocks.

1-Tower Flame-Gear Tower There is an 8-bit Luigi sprite hidden in the gap to the bottom-left of the final gear.

1-3 Rolling Yoshi Hills There is a grey spot shaped like Luigi jumping to the left of the second POW Block.

1-4 Piranha Heights ''The room that contains the third Star Coin has a large climbable statue of an 8-bit Luigi made out of colored blocks.

1-5 Piranha Gardens There is a large Luigi-shaped hedge near the first Hammer Bro. in the level.

1-Castle Lemmy's Lights-Out Castle Hidden in the wall above and to the right of the boss door is an 8-bit sprite of Super Luigi.

2-1 Spike's Tumbling Desert

 * A bone shaped like Luigi can be seen to the left of the P-Switch.

2-3 Piranhas in the Dark

 * Kill the first Piranha Plant pipe to find a secret 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.

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.

6-5 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.

7-5 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.