I'm A Banana
Potassium-Rich
A lot of the suggestions here are how to take something nasty and dress it up as Lawful and/or Good, but in an objective morality system like D&D has, those things are not, in fact, Good.
In D&D's rather light morality, it's sometimes hard to tell (just as it is in the real world, even when you believe fervently in a moral system). Oppression and subjugation probably aren't inherently evil. Free choice and independence probably aren't inherently good (indeed, this is a lot of the Law/Chaos axis). Oppression of a minority of wicked (or even just "not good") people in the name of greater goodness probably isn't evil. It's OK to kill all the goblins if all the goblins are doing bad things.
I like playing with the fuzzy lines between the alignments in many of my games.