I'm gonna let Tear post all the history of Thanos, since he will do a better job, but I am gonna post a pic of young Thanos with his family. Ugly little feller.
Best bad guy, just from sheer cringes running down my back if I were ever to be caught in a corner by him: Sabretooth. He's like Freddy Kreuger in battlecat form.
For sheer power, I'd go with Onslaught. I think that if he ever reached full potential, he would've been more powerful than ANYONE.
I don't know much about comics but was he really made out to be a Nazi? Or are you just making it up? If it is true then what the fudge. It is suppose to be a comic book for kids and they have a Nazi as one of the characters.
And wait a minute... HECK seems to support this guy quite much.... doesn't he....