Haha don't worry I could never forget Inglourious Basterds.(you say this even as the reference photo shows Waltz in an SS uniform as Hans Landa, one of the best movie Villains of the last 10 years )
Honestly, i can't really see Leo as Featherston: he's decribed as thin and a bit gaunt in the books, and even as an adult Leo is pretty round-faced. I could see Nicholson pulling off Clarence Potter, though.
I just thought of featherston as guy who looks like he's always on edge, ready to snap.
But I haven't read any of the 191 books since I finished the last nearly thirteen years ago.