The Guiding Hand Social Club theft - Eve Online
If Eve Online has taught us anything, it's how nefarious some players can be and consider espionage just as important as an epic fight with an adversary.
An Eve Online Corporation called "the Guiding Hand Social Club" spent a year of sending its players to rival factions, inserting themselves in all aspects of their corporate structure. With all the players in place, an order was given and like a movie plot, they simultaneously murdered the rival corporations CEO and stole virtual goods that amounted to the cost of $16,500.
The impressive part about the plan is that it was done within the rules of the game.