Kuvira

Kuvira is a powerful metalbender and the main antagonist of Book Four of The Legend of Korra. Originally a captain of Zaofu's guard under Suyin Beifong, she rose to power by uniting the fractured Earth Kingdom after the fall of the Earth Queen. She declared herself the 'Great Uniter' and established a militaristic dictatorship, conquering territories by force and imprisoning dissenters in reeducation camps. Kuvira is one of the most skilled metalbenders alive, capable of manipulating metal strips as weapons with deadly precision. She constructed a massive spirit-energy cannon powered by spirit vines, making her army the most technologically advanced military force in the Avatar world.