Rat
This NPC can be found in Tirisfal Glades (81), Howling Fjord (71), Terokkar Forest (52), Desolace (32), Stormwind City (26), Naxxramas (26), Ghostlands (23), The Culling of Stratholme (20), Bloodmyst Isle (18), Nagrand (17), Arathi Highlands (16), Scholomance (14), Dire Maul (13), Zul'Gurub (11), The Shattered Halls (11), The Deadmines (10), Scarlet Monastery (10), Shattrath City (9), Alterac Mountains (7), Western Plaguelands (6), Grizzly Hills (6), Sethekk Halls (6), Stonetalon Mountains (6), Karazhan (6), Silverpine Forest (5), Hillsbrad Foothills (5), Mana-Tombs (4), Azuremyst Isle (3), Drak'Tharon Keep (2), Dalaran (2), Undercity (2), Eversong Woods (2), Stranglethorn Vale (2), The Violet Hold (1) and The Temple of Atal'Hakkar (1).