An advertising slogan for a famous fur company once posed the question “What becomes a legend most?” That philosophical conundrum resonates with added meaning this year, when theaters seem glutted with movies about history’s most storied icons.

Friday alone, Washington area viewers are being treated to a big-screen adaptation of “Tinker Tailor Soldier Spy” and “Sherlock Holmes: A Game of Shadows,” featuring the fictional Cold War spy George Smiley and the titular Victorian-era detective. Filmgoers can also take in “A Dangerous Method,” about psychoanalytic pioneer Sigmund Freud and his friendship with Carl Jung.

Whether drawn from fiction or real life, these protagonists present particular challenges, not just for the actors playing them but for audiences who are likely to have preexisting images of them in our heads. Success, when it comes to playing the larger-than-life, isn’t just a function of a great performance but an act of will on the part of filmgoers who must simultaneously hold on to and let go of their most ingrained, cherished preconceptions.

So people interested in seeing Gary Oldman play Smiley in “Tinker Tailor Soldier Spy” will not only have to submerge their own vision of the MI6 operative if they’ve read the book, but they’ll also have to bid farewell to Alec Guinness’s definitive portrayal of him in the 1979 BBC miniseries. In fact, filling Guinness’s legendary shoes gave Oldman pause, until he realized that, like great Shakespearean roles, Smiley was legitimate territory for reinterpretation. Oldman’s level-headedness and guts pay off in “Tinker Tailor Soldier Spy,” in which he’s just as recessive and diffident as Smiley is on the page, all the while infusing the character with newfound amounts of quiet, carefully conserved energy.

Oldman spends much of his time listening in “Tinker Tailor Soldier Spy,” and he doesn’t speak in the film’s first 20 minutes or so. Such restraint — the willingness to appear to be doing nothing — marks the confidence of an actor who trusts the camera, and by extension the audience, to fill in the fascinatingly blank slate he presents. Staring evenly out of his owlish glasses, his face a mask of bland inscrutability, Smiley seems to take on the coloring of whatever habitat he finds himself in, a process of active passivity that Oldman animates with just the right amount of calibrated dynamism on-screen, such as when he slowly rolls down a car window to let out a bee that others have been furiously swatting.

The secret Oldman understands about playing a beloved literary figure is that one must simultaneously banish the character and subtly fuse it with one’s own. And it’s precisely that delicate balance that Robert Downey Jr. fails to strike in his “Sherlock Holmes” movies, in which he allows his own manic, look-at-me showmanship to swamp any attempt at genuine characterization.

Goodness knows that Holmes has proved a wonderfully elastic figure over the years, as amenable to the straight-faced style of Basil Rathbone in the 1940s and Jeremy Brett’s more neurotic interpretation in the 1980s to a modern-day version played by Benedict Cumberbatch (who can coincidentally be seen ably assisting Oldman in “Tinker Tailor Soldier Spy”). But in Guy Ritchie’s 2009 “Sherlock Holmes” and his new sequel, the consulting detective has become utterly unrecognizable, an eccentric foil for the movie’s true mission of bombastic action, “Matrix”-inspired special effects and campy bromantic dynamics between Holmes and Dr. Watson (Jude Law).

Playing a Holmes who’s part beefcake action hero, part foppish transgressor, Downey clearly has a good time with the plummy British accent and winking subtext, but he’s not playing the character as much as using him to consolidate a persona he’s already perfected in the “Iron Man” movies. He’s violated the cardinal rule when playing a known quantity (a rule Oldman so faithfully obeys): Make a character one’s own, but don’t smother it completely with one’s own mannerisms, tics and native charisma.

Icons, in other words, must be allowed room to breathe — even more so when they happen to be real human beings. For an actor, the operating question isn’t “What becomes a legend most?” as much as “How do you become a legend best?”

In “A Dangerous Method,” opening Friday, Viggo Mortensen plays Freud, not as the balding, white-bearded man with a scowl most people conjure when they think of the Austrian neurologist, but as a middle-aged family man of warmth and even humor. (“What an exquisitely Protestant remark,” Freud says when Jung betrays his naivete about anti-Semitism.) Mortensen’s co-star, Michael Fassbender, didn’t need to clear the same preconceptions about Jung as Mortensen did about Freud, which makes Mortensen’s performance all the more accomplished.

Playing the psychiatrist at a moment when his theories about sexuality and human psychology were controversial and precariously fragile, he imbues the real-life man with the stately reticence of a Viennese bourgeois, not the inner fire-bomb-thrower. It’s an approach that allows the film’s true stars — ideas — to shine. Fassbender and Keira Knightley, as Jung’s patient-slash-lover Sabina Spielrein, get the showiest scenes, but “A Dangerous Method” works thanks to the quiet, self-effacing work Mortensen does to take Freud out of the pantheon and into the cozy, well-worn living room.

Mortensen was deservedly nominated for a Golden Globe on Thursday for his performance in “A Dangerous Method.” So were Leonardo DiCaprio and Meryl Streep, for their portrayals of FBI Director J. Edgar Hoover in “J. Edgar” and British Prime Minister Margaret Thatcher in “The Iron Lady” (due in Washington theaters Jan. 13). As accomplished as those performances are, though, they also point out the dangers inherent in playing real-life icons whose faces, behavior and habits of speech are so well known that they invite impersonation rather than acting.

It’s impossible to argue that DiCaprio and Streep don’t uncannily inhabit their respective characters, in both cases with some extraordinarily realistic makeup and prosthetics. Both are called on to age over several years in their movies, each of which hews to a first-person, flashback-framed narrative structure that favors psycho-biography over larger cultural or political implications. The result, in each case, is a portrait that, while impressive in its mimicry, becomes a study in rhetoric and personal style, rather than an illumination of more complex truths beyond the subject’s interior demons. (In the words of one British critic: With “The Iron Lady,” Streep “gives us Thatcher without Thatcherism.”)

If both “J. Edgar” and “The Iron Lady” err on the side of wax-works imitation, that’s not the fault of DiCaprio or Streep as much as the movies they’re in. But both performances raise the question of whether an impression can be too good, dazzling audiences with sheer technique but distracting them from deeper meanings. Compare Streep’s note-perfect impression of Thatcher with Michael Sheen’s portrayal of Tony Blair — whom Sheen resembles only slightly in “The Queen” and “The Deal,” but who nonetheless emerges as a vivid avatar of political ambition and social change in 1990s Britain.

Or consider “My Week With Marilyn,” in which Michelle Williams takes on the daunting task of playing no less an icon than Marilyn Monroe. Physically, Williams is all wrong for the role — her lips are too voluptuous, her eyes too hooded, her vocal register too low. But in this snapshot of Monroe’s disastrous collaboration with Sir Laurence Olivier on the set of “The Prince and the Showgirl,” Williams manages simultaneously to evoke Monroe and spare her the indignity of impersonating her. Thus unencumbered, the film becomes less a showcase for a stunt of Great Acting than a wistful, affecting essay on art, celebrity, insecurity and ma­nipu­la­tion.

In her smart, un-mannered performance — also nominated Thursday — Williams conveys a more vivid idea of Monroe and the forces that shaped her than the most on-the-nose re-creation. She proves that, when it comes to playing a legend, literalism doesn’t become an actor. Rather it’s the confidence to be oblique, allusive and suggestively imperfect.