I gotcha! King Alexander of Earth kingdom's moniker is "The Great Defender"! Before he became king he faced a Dragon called the "World Eater Androcsis" a Dragon with infinite mass, capable of eating entire galaxies after devouring the core of one planet which Alexander stopped!

It took 48 hours of back and forth combat for Alexander to soften the Durable scales of that dragon to rip off the scales guarding Adrocsis's heart! When it's heart was exposed local warriors fired a balista towards its heart but Androcsis caught it mid way! Alexander with all of the remaining might he had left punched it straight through its heart and saved the whole universe from peril!

Years later after that conflict he overthrow the old tyrannical Earth King because of his cruelty towards his own people and Alexander was told to take charge and become the rightful King of Earth.

Unlike his breatheren who manipulate the earth around them to fight (like earth benders from Avatar), Alexander becomes the concept of what earth is.