Crusher refers to any stage element, hazard or block which can cause instant life loss by squishing Kirby or another playable character. While not a common hazard in the Kirby series, it is just as dangerous as a Void, as it can defeat Kirby no matter how much Vitality he has remaining.
In the simplest cases, a crusher will consist of a moving platform or landmass which makes contact with another platform. A character will only be crushed where those two elements make contact. In other cases, a stage element can be made into a crusher during an auto-scrolling section, when that element begins to leave the screen. If Kirby or another character are caught behind the object when that happens, they will be crushed (despite that making little sense in practice).
Crushers tend to only exist in stages themselves, and are not part of any enemy or Boss's arsenal of attacks. Items and other collectables tend to be hidden in areas prone to crushing, making retrieving them a risky prospect. In addition to playable characters, enemies and most items can also be crushed, which will remove them from the game.
- Crushers are necessarily fatal, as otherwise, Kirby would likely end up inside a wall or floor, breaking the game's immersion.