Hello! There tend to be a lot of those types of guild around in general. I’m sure if you stroll around Stormwind for an hour or so, you’ll come across several.
However, if you’re looking for something which starts of with a heavy mercenary feeling, but descends into a more heavy criminal setting I suggest: (A-Criminal) The Fifth Pledge [RP/PvP/PvE] - #17 by Daaé-moon-guard