Halloween has come to Tyria, and that means the return of Mad King Thorn, new holiday quests, loads of creepy items, the Costume Brawl PvP event, and more!

The ghoul-apalooza begins on October 23rd and runs until 12:01 AM Pacific time on November 2nd. The main festivities take place in Lion's Arch and Kamadan, but the Halloween spirit can be found in other places around Tyria.

http://www.guildwars.com/events/ingame/halloween_2009/