I have only seen the movie, so my opinions on these guys:
Rorschach: ISTJ gone wrong, or ISTP. I couldn't even imagine an INTJ playing a film noir detective. That's a S stuff at its strongest. And whoever said that ISTJs can be cold and brutal, you are dead wrong. Let me show you...
Dr. Manhattan could be INTJ or INTP.. don't know those types well enough to decide.
Ozymandias was quite certainly an ENTJ. Quite obvious.
The Comedian: I'd go for ESTP here. He was physical, he was immediate and he was rude. Person doesn't have to be Ne to notice what's wrong with the world. SeTi is actually quite good for noticing patterns in other people. SeTi people would probably be the first to embrace the human nature as it is, a nature of brutal animal.
Nite Owl II: A clear ISFJ on my opinion. He was always the caring one, but was also always afraid to openly oppose anyone.
And Silk Spectre... hard to say.. she was somehow always in the background. Maybe an INFP. Or ISFP.