The Gigantic Crustacean is a boss in Chapter 1 of Mother 4: The New Pig King. It resembles a gigantic crab. It is fought in the huge clearing at the grassy valleys after meeting Winston . After he taunts Gavin about capturing Judy, Winston flies off in his helicopter as Gavin attempts to shoot it down with an intense burst of energy, which misses. Winston then orders the Pigmask Colonel to activate the Gigantic Crustacean, which he sadly does and begins the fight. It possesses these attacks:
- Mechanically edging closer. (does nothing)
- Mechanically brandishing a pincer.
- Mechanically pulls of a crushing chop.
- Letting out an intense burst of steam. (does nothing)
- Mechanically grabbing a party member. (solidifies them)
Its battle music is titled "Formidable Foe", and is the only enemy to use this theme. It was featured in Mother 3 and played when you fought the Oh-So-Snake.