The King of the Land is an implied character in Cave Story; he ruled an unknown kingdom on The Surface. Jealous of how much the people loved Ballos, The King of the Land captured him and tortured him, until Ballos' power ran wild. In a furious rage, Ballos killed him and burned down his kingdom, killing all other members of the area. The King of the Land is never seen in-game. He might be the true villain of Cave Story.
A text box displayed midway through B2 of the Blood Stained Sanctuary implies the the King of the Land was human.