Was that Miranda Lawson cosplay a little too clean-cut for you? You might prefer Jack, then, the resident whackjob of the SSV Normandy, here portrayed wonderfully by Jia Crens.
There's a level of dedication here that borders on the fanatical. In a good way. See, Jia not only models in the shots here, but also made the costume (it's a flesh-coloured bodysuit, not ink-on-flesh) and, most amazingly, even submitted herself to the barber's clippers, going so far as to have Jack's hair "design" shaved into her scalp.
You can see a few shots here, but for the full gallery, head over to Crens' site, which also gives a detailed breakdown on how the costume was made.
Jack - Mass Effect 2 [JIAJEM, thanks Brian!]
Subject Zero [Cosplay.com]