Nostalrius, the pirate World of Warcraft server, will be making a return on December 17th, reborn as Elysium. The original Nostalrius server was shut down by Blizzard, but the WoW team met with server 'owners' earlier this summer in a cooperative effort to define the issue. After a few months of what was perceived to be inaction on Blizzard's part, the Nost team threatened to release its source code if the issue was ignored during Blizzcon 2016. It was and the code was subsequently released.
According to the group behind Elysium, all character data from Nostalrius has been imported so players can continue from that point forward or start off on the new 'fresh start' server.
Check out a Reddit FAQ about Nostalrius / Elysium to learn more.