This is a character that we normally don’t root for (unlike the trope “Rooting for the Empire”), but if we had to face off with some sort of villain, we’d likely rather it be one of them. This is a character that is always charming and never loses his cool even when he is on the losing side. Even though this character does awful things and we tend to want to see justice get served against their favor, they are still rather nice and pleasant. This is sort of like a gentleman villain although they don’t necessarily have to be gentlemen.
Alfred Hitchcock seemed to love this trope. It was already irregular that Hitchcock seemed to cast objectively good-looking actors to play his villains (Robert Walker, James Mason, Anthony Perkins, Joseph Cotten, Herbert Marshall, etc.), but he also would have them be oddly laid-back and gentlemanly. One of the earliest examples of this trope from him is in The Lady Vanishes (1938) when one of the characters our heroes trust turns out to be in on the missing persons case and is a Nazi at that (and he is played by Paul Lukas who falls under the category of Hitchcock’s more attractive villains). When he ends up losing at the end, he strangely doesn’t seem to be that mad about it as he even wishes our heroes luck with a smile on his face. Needless to state, this depiction of a Nazi seems unusual but it was 1938 before all hell broke loose and the allies knew more about Nazi oppression and their crimes. That didn’t stop Hitchcock from making yet another gentlemanly Nazi in Notorious (1946) which came out a year after WWII. Critics have mentioned that Claude Rains’ Nazi in Notorious might be the most sympathetic Nazi ever put on-camera in American film. While our heroes of the movie are on the right side (they are secret agents trying to catch Rains) they are morally grey and capable of making mistakes and bad decisions which contrasts to the seemingly always nice Rains. I would argue, this makes the heroes more relatable and the villain a bit more distant as a result since despite these moral differences we are always on the side of our heroes throughout the film’s run. “Affably Evil” villains also take center stage in other Hitchcock productions like Saboteur (1942) and Dial M for Murder (1954). George Sanders plays the villain in Hitchcock’s Rebecca (1940) and every time he played a villain (which was a lot) he would project this trope naturally due to his gentlemanly charm.
Hitchcock wasn’t the only filmmaker who would take a more complex approach to Nazi characters, for instance look at the colonel in The Great Escape (1963) who is rather polite and a far cry from characterizations of characters in similar circumstances and is even apparently based off the commandant of the real Stalag Luft III who reportedly was just like his movie counterpart. Still, most film versions of Nazis were cruel and heartless and while you could argue the Hitchcock approach can be more interesting as a narrative tool, the more popular depictions seem to be way more accurate with a majority of Nazis who were even more brutal than shown in the meanest depictions. Nazis were undeniably monsters so showcasing them as such is not a bad thing, and the same can be said for actual monsters. Obviously, most monster movies are going to portray their monsters as crazy, demented, and scary. All can be said for Dracula, but (unlike pretty much every other movie monster) one cannot deny that he is also rather polite for someone who wants to suck your blood and break your back as in Renfield’s case. He is a count after all, and counts have a reputation of holding onto a tradition of manners.
There are also people who worship monsters, like Niall MacGinnis’s cultist in Night of the Demon (1957) or Curse of the Demon. As far as Satanists go, he is probably the nicest one you would meet. Sure he may place the mark of death on people getting in his way, but he also is kind to his mother and gives parties for children. In fact, we are first introduced to him through one of these parties. TV Tropes also mentions Orson Welles’ Harry Lime from The Third Man (1949). While MacGinnis is kind to children in Night of the Demon, Lime goes so far as to put kids in physical harm in The Third Man. While his acts are undoubtedly cruel and Joseph Cotten’s character does the right thing in the end, Lime is not exactly menacing when we see him in person. He is well-spoken and rather articulate for someone so heartless, but it probably wouldn’t make sense for Valli to be hung-up over someone so horrible if he embodied the nature of his ghastly deeds. The site even mentions the gangsters from Shoot the Piano Player (1960) who are not polite or gentlemanly like a majority of “Affably Evil” characters, but rather delightful and amusing. While we are never on their side, they are certainly a whole lot of fun to watch when they are on-screen and their banter is very much like that of the hitmen in Pulp Fiction (1994) (it is obvious Tarantino was heavily inspired by Truffaut’s films and it appears this film in particular inspired him). While they are not charming, they are funny which makes them way more agreeable than most villains especially other film gangster archetypes.
Whether or not you decide to make your villain more obviously evil or more subtle and complex, there are good examples of each. The latter approach, which often goes hand-in-hand with this trope, is a good way or portraying a villain. It makes them more mysterious and questionable rather than cartoonish and extreme. How can a guy as nice as Claude Rains in Notorious be a Nazi? How can characters as amusing as the gangsters in Shoot the Piano Player be willing to commit any crime imaginable? Why does a Satanist go out of his way to be kind to others in Night of the Demon? It makes you dig a little deeper into their characters than you might have if they didn’t hold these little offbeat moments. Even characters that should be pure evil can still avoid being seen as 100% bad. If this trope is taken way too far than the audience may find themselves siding with the villain (which most of the time the film does not want you to do), but if handled just right they make a villain more three-dimensional yet still evil enough to root against. That is the best way of handling this trope and these examples have pulled that off well.