I believe these five stand out the most for me.
1. Alucard, Hellsing- He is ze über badass.
Hell his guns are hella powerful as well. Not to mention his "I'm coming back until I kill you" thing. :p
2. Gatz, Berserk- Same as above only he has a badass sword instead of guns...He also has superhuman strength and endurance.
3. Saitou Hajime, Kenshin- He's a real person and does his missions cool and swiftly. Also, a secretive person as well. Not even his birthday is known. :O
4. Kenshin, Kenshin- His sword techniques are amazing and he's funny too. :p
5. Seras, Hellsing(*sees eyebrows being raised*)-Well...uh...she showed how badass she was on Hellsing ep. 6.
Plus, she's hot.
Uh huh.