Nuju is a crabby seer/stargazer with his head in the clouds, but can be rather scary when in battle. It turns out that his Ice power is the one thing that the mighty Morbuzakh plant is afraid of, and while he and the rest of the Toa Metru are being suffocated by its tendrils, he manages to get away and rescue the others using basic physiology. He also has a lot of hilariously sarcastic one-liners that nobody else in the series could pull off.
Nuju: "Whatever it is, leave it. If you can't leave it, then take it back out with you. If it's too heavy to carry back out, then how did you get it in here in the first place?"
Whenua as well.
Mutran and Chirox can also count as this, being that they are both mad scientists responsible for several of the more destructive Rahi (animal) species in the world - Chirox’s in particular are described as “adding nothing to the ecosystem beyond death and destruction”. Chirox is also a devastating warrior, even after being rendered completely blind by the Mask of Life’s explosion of power.