Herobrine is a Minecraft myth saying that there is this Herobrine mob, its the default character with completely white eyes. He usually breaks windows, makes 1x1 and 2x2 holes in the ground, and places blocks in the sky, and then finally scares the player out of continuing to play. I think that he wants to be left alone, and instead of killing the players he just scares them, and he breaks windows because he apparently hates himself, and doesn't want to see his reflection.