James Cromwell did not receive an Oscar nomination Captain Dudley Smith in L.A. Confidential.
This is not to say that Cromwell's portrayal is overly simplistic, as just like Pearce and Crowe, Cromwell slowly peels away the role you thought he was fulfilling from the beginning. Cromwell does disarm you for most of the film with his considerable old guy type of charm, even though we slowly see that Dudley is not exactly on the level from start. Cromwell brings a certain edge to the character form the very beginning, and the film itself brings as one of the first things he does is grill Ed on his ability to break the law to uphold the law. Cromwell plays incredibly well because the way he delivers the lines is that of good mentor just testing the man as one should. Of course throughout the main investigation Cromwell plays Dudley as very calm and considerate to both officers, and reserved in that he seems to be ready for any result. Cromwell does it well because it could just be taken as a man who's seen enough to know what to expect, or maybe old Dudley just isn't really the man he appears to be.
Well that's where the major spoiler for the film comes into play which is that Cromwell actually is the chief villain in the film. Dudley is actually behind pretty much everything that has being going in the film in his attempt to take over organized crime in the city by using any means necessary. Cromwell reveals that all of his personal style is no that of a father figure but merely that of a power hungry master manipulator. The whole impact of the revelation is made extremely palatable because of Cromwell's performance. On one hand it is is a twist that holds up to scrutiny as you simply see Cromwell's earlier performance only makes more sense in this new light, and another its a very effective twist because how good of a villain Cromwell makes Captain Dudley. It is very disconcerting to see Cromwell play such a cold man in the last third of the film, instead of warmth in his eyes there is only a killer's calculation there. Cromwell is especially chilling in one moment where he reveals to one of his accomplishes that he's expendable with the simple statement of "Hush Hush".
The casting here was certainly quite clever as it has the effect that I'm pretty sure was well intended by the filmmakers. They do not deserve all the credit though as Cromwell wholly delivers in the role as well, and turns Dudley into quite the memorable character. Like Pearce and Crowe slowly reveal a depth behind the straight forward by the books cop and the rough thuggish cop respectively, Cromwell reveals the truth behind the mentor. In Cromwell's case it has the opposite effect, where Pearce and Crowe allowed a greater sympathy and understanding for their characters, in Cromwell case, he subverts the whole idea of the comforting experienced mentor type character that was expected. It's a brilliantly devious and devilish turn, that brings a strong menace to the film the moment that it is needed. Cromwell's performance might not be the best performance in the film, but its a very good performance that is yet another fantastic facet of this terrific film.