Assassins appear in the game X-Men Origins: Wolverine. Multi-armed ninjas, very similar to the Hunter. Interestingly, the assassins don't play nicely with other enemies, which may give you cause to stay back for a bit. Counters are effective, but lunges are better, because of the nasty stab move that triggers a QTE. This isn't so bad on its own, but if a few assassins surround you, they can get you caught in a loop of stabs, at which point you may have to take a hit to break out of it.