What made Christoph Waltz such a compelling villain in “Inglourious Basterds”? It wasn’t the fact that he was an opportunist Jew hunter who didn’t care what side he was on as long as it was the winning side. It was because he was a funny, charming Jew hunter whose quirky aphorisms (“That’s a bingo!”) made him that much more terrifying as a villain.

Christoph was as inspired a casting choice for Quentin Tarantino as when he single-handedly revitalized John Travolta’s career: No one in America knew anything about the baby-faced Austrian, so his arrival as Col. Hans Landa came completely without cultural context, a strange move for a director so mired in exactly that. But back in Austria and Germany, where Christoph holds a dual citizenship, the actor spent almost 30 years playing romantic leads like Tristan (from the mythos of Tristan and Iseult) and, in “Das merkw

For the highly acclaimed spaghetti western, director Sergio Leone had to personally fly to New York and beg Hollywood’s handsome leading man to play the role of a psychotic child killer and rapist. Not only did Fonda eventually agree to the part, but he went so deep that he made Christian Bale in “American Psycho” look like a spoiled little princess. Despite wanting to wear dark contacts for the part to make him look more like an evil gunslinger, Leone convinced Fonda to keep his natural baby blues, creating the bone-chilling effect of seeing a heartless stranger look out from the familiar face of America’s dashing hero. Henry gives a great recount of his transformation in this 1975 interview.

Some might argue that Deneuve was more a victim of her own psychosis in Roman Polanski’s apartment thriller, and it’s hard to make the case that the character with 90 percent of the screen time could be so dangerous. But after the gamine Carole is left alone for the weekend and starts hallucinating that the walls are (literally) crumbling in around her, she goes ape-shit: From stabbing a woman at a nail salon with a file (imagery that would later be used in “Black Swan,” a psychological nightmare that owes a lot to “Repulsion) to beating a would-be suitor to death and then leaving his body in a tub, Carole carries out each of her murders with a kind of trance-like conviction that, yes, every man in the world is out to rape her. Scary part? Kind of turns out to be true.

Oh, Jesus, remember that late ’80s/early ’90s period when directors kept casting Keanu in period pieces? From “Dangerous Liaisons” to “Dracula” to the Shakespearean comedy “Much Ado,” Keanu somnambulist-ed through each film like Ted going on a very bogus journey. At least while playing dopey love interests, you could almost see the reasoning in hiring the pretty-faced Keanu, but for the scheming Don John, Keanu came off sounding worse than a high school student at Ren Faire.

Denzel suffered a similar challenge as Fonda did in “Once Upon a Time” when the actor took on the role of the corrupt detective: Would anyone believe that the man who played Malcolm X, who always played the hero, could even be slightly in the wrong? Luckily, this conception worked in the film’s favor, as both audiences and Harris’ new partner, Jake Hoyt (Ethan Hawke), are never quite sure just how “Bad Lieutenant” this guy is. By the time we find out, he’s already convinced the new guy to smoke pot laced with PCP and act as an accomplice to first-degree murder, and, ultimately, has him killed. Denzel could have played this character with the grave authority he’s brought to other films, but instead he chose to make Harris … spunkier. Just having fun, this guy. Until he offers a local gang money to have you bumped off, that is. The departure from Denzel’s usual leading man position was rewarded with a best actor Oscar in 2001, and a spot on AFI’s Top 50 villains list.

There is absolutely nothing scary about the quirkier of the Cusack siblings, which is why Joan’s role as the black widow nanny in the dark comedy “Addams Family Values” was such a delicious turn for her. Not only was she playing against her “Oh jeez!” type, she was a gold-digging killer who managed to make Rebecca De Mornay suddenly seem like not so bad a choice to watch the kids after all.

You’ve got to hand it to David Mamet. In his twisting thriller “The Spanish Prisoner,” he cast sleazy corporate guy Campbell Scott as the hapless mark, and gave the role of the ultimate con man to everyone’s favorite banjo player, Steve Martin. Jimmy was like a smarter, evil incarnation of Martin’s dopey character from “Dirty Rotten Scoundrels,” which made him that much more sinister as audiences and protagonist alike constantly gave him the benefit of the doubt.

Can we just agree that the worst villains usually think they are working for the side of justice or righteousness? Nurse Ratched in “One Flew Over the Cuckoo’s Nest,” Piper Laurie in “Carrie,” John Doe in “Seven”: all monsters, all think they are doing the “right thing” by killing and/or maiming people. Add Dolores Umbridge to that list. The Dark Arts Defense teacher is even creepier because she dresses all in pink, is constantly smiling, and looks like your Grandma … even while she’s having Harry carve the phrase “I must not tell lies” into his own hand. That’s enough reason right there never to go visit Bubby ever again.