I have perhaps posted this before, but after my lackluster attitude to The Avengers I needed some real super hero bad-assedness. What did I do to get my fix? Justice League Unlimited, Series 3, Episode 9... "Grudge Match."
"Grudge Match" is a favorite of mine. Not just for the sexy-lady-fighting angle, but because it really features our favorite hero as the bad ass She is. The Justice League, and Justice League Unlimited cartoons have predominantly been good to Diana, letting her beat Superman's ass pretty harshly in Series One ("Paradise Lost", S1E10/11). In "Grudge Match" we get to see the kind of fear She strikes in her enemies. Below is a playlist of the entire episode. The good stuff starts in part 2, around 04:45. You know you are a bad ass when you get Hawkgirl to basically say "Game over, man! Game over!"
And just for fun, and so you don't have to follow the link, here is the aforementioned Superman ass-whoopin'. Sure, they don't let you know who would win, but I say if Superman is in in full defense and you are still bringing it to him then the man is in trouble.