On July 31, 2010, Minecraft Forum user Flaky posted a comment, supposedly copied from a post on 4chan's /v/ board, containing a story of a player encountering an entity with glowing white eyes after listening to the '13' music disc. For more detailed information regarding the Brocraft events, see the Minecraft Wiki's interview with Copeland and his recounting of the events. Zoomed-in excerpt of Herobrine in the original image. The popular story and screenshot detailing a Herobrine 'encounter', posted on 4chan's /x/ board on August 31, 2010. The original screenshot which inspired the 'White Eyes' story, from July 30, 2010, with an enhanced excerpt below. Any appearances of Herobrine are caused by either mods being installed or because of another player using the skin.
It is not possible for Herobrine to have ever existed in any unmodded clients or servers.
There are no references to him at all in the source code, and there is no code to allow for any entity to act like Herobrine. Herobrine is not in vanilla Minecraft, and never has been.