Black Rat
This NPC can be found in Duskwood (22), Razorfen Downs (28), Western Plaguelands (20), Icecrown Citadel (25), Pit of Saron (8), The Forge of Souls (9), Halls of Stone (7), Shadowfang Keep (12), Utgarde Keep (18), Utgarde Pinnacle (7), The Sunwell (4), Coilfang: The Slave Pens (4), Ahn'kahet: The Old Kingdom (5), Drak'Tharon Keep (4), Scholomance (1) and Violet Hold (3).