The Crown of Bethmora is a relic that was featured in Hellboy II: The Golden Army.
Long ago, when man declared war on magical creatures, the Goblins of Bethmora created the crown to enable those of ancient bloodlines like that of King Balor to command The Golden Army. After the battle ended with Balor arranging a peaceful coexistence between his kind and man, he divided the crown into three pieces with one third given to the humans while he kept the other two pieces. Only Balor's son Nuada considered this an error as he enter an imposed exile.
Millennia later, Nuada resurfaces as he eventually reassembles the crown to have the Golden Army wipe out humanity. But Hellboy, through his paternal lineage, is able to win the crown from Nuada before Liz Sherman melted it so its power could not be used.