Billy or Bill is the hidden main antagonist in Phoenotopia and presumably the main antagonist of its sequel Phoenotopia II.
Billy is first contacted after bringing the golem head which Gale found in the Old Ruins to Thomas. After bringing him to Panselo alongside Prince Leo and some other guards, he reveals himself to be a Stellanite, a race that is believed to be the distant cousins of Earth humans. He is a tall figure with blueish skin and long ears. Although he seems to be concerned about saving the earth from the Galactic Federation invaders, after reaching the Phoenix weapons, he reveals his true intentions of waging a total war against the Federation with the purpose of annihilating them entirely. When Gale objects to this, he has her shot by one of his soldiers and, seeing that she didn't die, orders Phoenix 66 to kill her. After both Gale and 66 are abducted by a collector ship, Billy reveals that his intention was not just destroying the Federation but becoming the King of Earth as well. He'd allow the Federation's harvesters to wreak havoc on Earth and would only appear with his Phoenixes after most of the humans were either dead or captured. When humans came to him and begged him to be their king, he'd refuse at first but then concede to their request.