Granny Beldam
Granny Beldam is an NPC who stands outside of a small shack on a small island in Nerva Archipelago north of Arbiter Frederick and south of Agincourt. She is not a contact, but she will grant a fifth costume slot if brought a complete set of costume Event Salvage from the Halloween Event 2006. Her coordinates are (2692.5, 11, 6050.5) .
When clicked, Granny Beldam says:
So you think you know the season of the witch, eh? Well, during the days of the midnight harvest, you should come across some things that I could use... Halloween costume pieces that I would love to add to my collection. Bring me one Statesman Mask, one Lord Recluse Helmet, one Back Alley Brawler Gloves, and one Hamidon costume. If you are capable of that feat, I will bestow upon you another Costume Slot, just don't make the new outfit as ugly as the one you're wearing now.
Ah, perfect... you have all that I require. Now take your costume slot and begone!