Then and again, the awesome works of Notch and a few guys has uncovered this hoax.
Herobrine is just a retexture of the default character skin in minecraft (with white eyes.)
He's very creepy, and just runs away after staring at you.
Players claim to have seen him and after attempting to stalk him, they see his works of art.
Herobrine is obsessed with small pyramids in minecraft and 4x4 holes.
He was programmed to dig mini tunnels and make holes on walls.
Being a real scare to players in minecraft, some mod-makers decided to make herobrine mods that spawn herobrine.
Player2: Lies, he's just a hoax created by Minecraft Devs to scare you.
Player1: STFU, it's true!
Player 1: Did you take my diamonds?
Player 2:(who actually took the diamonds), No it was herobrine
Player 1: I know it was you.
Player 2: No it was Herobrine
He used the default skin, but has pure white eyes. This was also claimed to be Notch's dead brother, who somehow got into the game...
Herobrine never attacked. He stood there off in the distance staring then disappear.
He made mineshafts, and houses and other things. This is probably why now, the game Minecraft has abandoned mineshafts and npc villages. (And maybe even dungeons!)
As a joke, Mojang (The company that made the game) puts in every update log - "Removed Herobrine"
But, he was never real. As seen from a tweet from notch himself saying that herobrine was never real, and it was a hoax. Yet still today, younger people who are first starting off (AKA noobs) and hear about this, still believe.
Here is a picture of Notch himself saying he was never real and that he doesn't have a dead brother.
Or go to the wiki -
Guy 2: "He. Is. Not. Real. How many damn times to i have to tell you??"