Black Rat
This NPC can be found in Razorfen Downs (28), Duskwood (22), Western Plaguelands (20), Icecrown Citadel (19), The Shattered Halls (16), The Forge of Souls (9), Pit of Saron (8), Utgarde Keep (8), Halls of Stone (7), Ahn'kahet: The Old Kingdom (5), The Slave Pens (4), The Violet Hold (3), Utgarde Pinnacle (3), Drak'Tharon Keep (2), Shadowfang Keep (2), Sunwell Plateau (2) and Scholomance (1).