|Debut Level:||Banjo Barnyard|
|Allies:|| King Grex|
|Behind the Scenes|
|Home Franchise:||Goop (Series)|
|Appears in:|| Goop's World|
Goop's World 2
Goop's Big World
Minion Warfare 2: Warmageddon
Grumblies are brown, spherical creatures with large, red, cup-shaped feet and no arms. They have a large circular mouth with a ring of triangular teeth all the way around it. They have two angry looking eyes and between them, a green stripe that starts at the top of the mouth, splits in two, and rejoins on the back of the head. They are about half the height of a male Gooptar (i.e. about 2 feet).
Grumblies are shown to be extremely weak, only dealing one damage and only taking a simple spin to destroy. Their only means of attack is to run head-first into Goop, but once they start running, they can't change direction.
There are three variations of the Grumbly.
- Pump-Kog: Pump-Kogs are robotic Grumblies with a spring on their heads.
- Mummbly: Mummblies are mummified Grumblies.
- Native Grumbly: Native Grumblies are Grumblies with native face paint.