Most Badass Language

My vote is German.

Sounds very rough and intentional, aristocratic,  there must have been nothing more scary in the 1940s to people then listening to germans speak.

I think German is great for making things sound very authoritative and mysterious. Take a look at these game cut scenes for example:
http://www.youtube.com/watch?v=mgMgf3T9cOw
http://www.youtube.com/watch?v=xBDxY6Q8pjo
http://www.youtube.com/watch?v=E_9dIflCLRo

Also, Russian generally sounds really badass. And ever since I've seen some documentary about the Foreign Legion, I've viewed French in another light too.