As far as Dial M for Murder goes, I'm a big fan of John Williams' (the actor, not the composer) performance as Inspector Hubbard.

He's so outwardly unprepossessing that you can't help but think he's going to be a blundering detective in the mold of Thomson and Thompson, but he's far cannier than he lets on.

Perfect casting in my opinion. I kind of wish Denholm Elliott had played Marcus Brody that way at some point in the Indy films--it'd have provided a good balance between the bumbling museum curator of Last Crusade and the savvy ex-adventurer of Raiders.