(n.) One who assaults, or violently attacks; an assailant.

adventuresome adversary aggressive aleatory ambitious antagonist anti assaulter attacker audacious bold brash brave chancy con courageous daredevil daring death-defying devil-may-care dicey doughty driving dynamic enterprising fire-eating foolhardy forceful forward full of risk go-ahead harebrained hazardous hotheaded hustling impetuous imprudent intrepid madbrain madbrained madcap match opposer oppugnant overbold overconfident presumptuous pushful pushing pushy rash reckless riskful risky speculative temerarious up-and-coming venturesome venturous wild wild-ass wildcat