Herobrine was nearly an entry in a recent article I wrote on Myths and Urban Legends in video games. So, if you don't know who HeroBrine is, here is a very brief explanation.
Over on Creepy Pasta, someone created a legend about the "Notch's Dead Brother" who appeared in Minecraft. This player only saw him once and the story didn't mention anything odd other than his existance and his relation to Notch. In Minecraft, players would "rarely" encounter some "other" in the game. This character had no nameplate but had glowing eyes. From here, his legend grew. It was said that Herobrine creates random things like pyramids and tunnels. He also burns down places in-game, trims all the trees, and creates elaborate dungeons.
Notch has gone out of his way to perpetuate this myth. For years he said that he would add Herobrine but eventually capitualted that he had no plans to actually add him.
Enter Craftbukkit.
Herobrine AI, Be Herobrine, and Herobrine (Bring back the legend) give this urban legend new form. So, given that the legend had been growing at an exponential rate, these plugins all manage to portray the legend a little differently.
In Herobrine AI, Admins and those with the node permissions to control Herobrine can send him to Haunt or Attack other players. He does things like create caves, he writes books and leaves them in treasure chests of that player, and he places signs as the player walks about doing whatever it is people do in Minecraft. He can also be tasked with walking about the world. He will just randomly walk around. This last choice is extrordinarily creepy and I hope that when Herobrine notices someone, he immediately begins to haunt them. Unfortunately, this plugin is waiting for an update as it seems to have its movement for the Herobrine model bugged somehow.
The second of these, Be Herobrine, allows players to become Herobrine. This gives you the standard steve model with the glowing eyes and the power to teleport to players, vanish, control another players chat, make tiny explosions, summon creatures, disorient other players, walk through fire, and just look generally creepy. It is neat that this mod and the previous give Herobrine such a different feel.
Then, there is the Bring back the legend mod. I have been running this mod on my server for a day now. It has been hilarious to watch though i feel guilty at the destruction that has ensued. So, in this mod, there is a random chance that Herobrine will spawn that server administrators have access to. He does similar things to the Herobrine AI mod, he will place signs and torches. He will play creepy sounds and footsteps that come from behind the player. He will also place books in treasure chests and steal from them.
The creepy thing this mod does is that it works more at night than the day. It also hunts for players who are by themselves. Once this happens, there is no limit to what Herobrine will do to them. I have seen him bury players, just appear and disappear at their minimum draw range, he will send them messages, manipulate the world around them, and I hear he can even detonate explosives on top of players.
Needless to say, these mods have managed to give depth to a community that can and does bring new people in as they read about Herobrine and grow curious about what sort of game coud have prompted such a legend. Long live Notch's brother – To Herobrine!