Koloss

In the Mistborn series, Koloss emerge as towering, blue-skinned monstrosities forged through the brutal ritual of Hemalurgy, their rapid, unending growth causing sagging, cracked skin and rendering them emotionless killing machines clad in stolen rags and wielding massive iron axes. First unleashed in The Well of Ascension, they serve as a devastating army under the Steel Ministry's control, nearly overwhelming human resistance with their brute force and numbers. By The Hero of Ages, their insatiable growth reaches horrifying extremes up to 13 feet, but the cataclysmic rise of Ruin reveals their vulnerability, culminating in a massive rampage that reshapes the battlefield before their tragic, explosive demise as the ashfalls cease.