Taskmaster Fizzule

Taskmaster Fizzule is a Dark Iron dwarf located outside a tower just northwest of the Sludge Fen in Northern Barrens.

Pre-Cataclysm
For reasons unknown, this Dark Iron dwarf was part of the Shattered Hand, a guild of rogues from Orgrimmar. Fizzule worked as a secret agent, infiltrated in the Venture Company.

He was initially, and would only become to those that fired a  twice and then "saluted" him, which is only an option available to Horde rogues undertaking the quest chain which starts with Shenthul at the Cleft of Shadow.

He then gave upon completing Deep Cover, making approaching him easier.

Cataclysm
Taskmaster Fizzule is now present in the northern part of the now divided Barrens, Northern Barrens. However, since rogues no longer receive the quest or a flare gun, Fizzule is now always hostile. It's unknown if he is still with the Horde (in secret) or permanently part of the Venture Company, however, players that still possess Fizzule's Whistle and blow it near him will still make him friendly, making the first possibility more likely if it's not a developer oversight.

Quests

 * Deep Cover
 * Mission: Possible But Not Probable