Ciaphus Cain, anyone?
I liked Caiphus Cain, but he suffers the same fate as Gaunt's Ghosts. They are only imperial guard so the writing was specifically designed so that the characters will only come up against and fight characters that are realistically in their reach of killing.
Caiphus and Gaunts ghosts will never take down some greater demon or a necron lord etc.
Just to add a note here, a bit off topic.
Is this a growing trend here for scifi/fantasy?
You have popular tv shows/movies where the only way a villian can be defeated is if the hero becomes just as powerful. We have the typical super hero shows where the good guys have to be able to match the enemy in strength as usual or by teaming up and by combining become just as powerful, then you have very popular anime series like DBZ where the character trains and ups his strength and is now able to blow up a planet.