Kruller

Kruller is an enemy ghost encountered in Luigi's Mansion 3. Kruller is an obese police officer who resides in the Hotel Shops located on the third floor of the Last Resort. Luigi fights him for the second floor's elevator button.

Biography
When Luigi enters in the room where Kruller was doing patrols, he is surprised at seeing Luigi and falls from the desk. He then puts his glasses on and goes through the bars to another room that has a box full of items. Kruller grabs his main weapon, a water gun and prepares to attack Luigi with it. Since Kruller is always on the other side of the room through the cell bars, Luigi is unable to battle him and so summons Gooigi to pass through the bars and start the battle with Kruller. He will use his glasses to prevent getting flashed as he bounces around the room.

In order to defeat him, Gooigi must vacuum Kruller's glasses. However, when Gooigi tries to vacuum them from Kruller when very close to him, Kruller will be able to use his belly in the right moment to attack Gooigi. If Gooigi receives enough damage, he will be undone and Luigi will have to create him again to battle Kruller. If Luigi fails to capture Kruller, sometimes the next time he appears he will be comically portraying a pair of groucho glasses, although he can use another pair of his original glasses later on. After being defeated, Kruller struggles to not get vacuumed to no avail. After defeating Kruller in two-player mode, Luigi, who was watching the battle from outside, takes all the credit saying that he did it, after which Gooigi humorously copies Luigi as he had actually defeated Kruller.

Trivia

 * His name is a pun on "cruller," a type of donut and a reference to the stereotype of police enjoying donuts.
 * Kruller is one of the few bosses in a Mario game, besides tutorial bosses in the Mario & Luigi series, where the player is guaranteed to win; they must fight him as Gooigi, and if he is hit by his water pistol, Luigi can simply spawn him again.