Those who pre-order the upcoming World of Warcraft: Legion expansion will gain early access to the new Demon Hunter class.

While the expansion itself will release on August 30, if you pre-order you can make a Demon Hunter beginning on August 9. This comes from a Q&A hosted on Twitch by the developers.

Another requirement is that you have a level 70 character in the same realm you plan on using the Demon Hunter class in, which will start at level 98.