It turns out the man who's rapidly becoming known for playing cold, calculating geniuses has a completely different side. Once you hear him play Cabin Pressure's Martin Crieff, the almost pathologically insecure captain of a decrepit charter plane, you'll never look at him the same way again—and that's a good thing. It shows just what a well-rounded, versatile actor Cumberbatch truly is, and it reminds the rest of us just what an important quality versatility is.

In fact, a lifelong obsession with classic movies has convinced me that versatility is one of the best tools an actor can have. In the course of one Turner Classic Movies marathon, you can go from watching Cary Grant trying to lure a leopard off a roof through song, to suffering deep romantic anguish over Ingrid Bergman, to announcing, "I'm the son of a sea cook!" and charging through a graveyard with Priscilla Lane slung over his shoulder. The man could do anything, and his wide range was among the factors—possibly even the biggest factor—that made him one of the greats.

But this kind of versatility, it seems to me, is becoming rarer among actors these days. The British, to their credit, still seem to encourage it, but Hollywood, not as much. Tom Cruise or Will Smith may start out doing a variety of roles, but once they hit the big leagues as action/adventure stars—which is usually the genre that defines the "big leagues" now—they're tacitly expected to remain action/adventure stars for all time. The occasional excursion outside that genre may be indulged, but not fully approved or rewarded. (Rock of Ages, anyone?) Similarly, Ryan Gosling, typecast for a while now as a "roguish heartthrob" (and star of a hundred thousand Internet memes) will likely be a roguish heartthrob forever after. As Hollywood's range of available genres has grown smaller and more simplistic, performers' options have narrowed. Generally, actors can make a name for themselves in action and/or sci-fi, or in the broadest, basest kind of comedy, or in drippy romance... and that's about it.

I'm not sure we even understand anymore what genuine versatility looks like. Nowadays, for instance, people tend to say of Cary Grant that he was always "playing himself." The same goes for James Stewart, Katharine Hepburn, and other actors who brought a recognizable, reliable persona to nearly every role. But paradoxically, that strong persona seemed to allow for greater flexibility. Maybe having a strong sense of who you are—or, as in Grant's case, who you'd like to be—makes you more comfortable in a wide variety of circumstances and genres. And that in turn gives you even greater confidence and security as an actor.

Does the same hold true for Benedict Cumberbatch? It's a little early in his career to say for sure. And it's true that the hilariously awkward Captain Martin Crieff and the ruthless "John Harrison" (I'll use the alias for the sake of those who haven't yet seen the new Star Trek) have little in common. Or is it? Mannerisms and motives—and willingness to wipe out human life on a massive scale—aside, they're both passionate, driven, eccentric loners who are nevertheless deeply committed to the relationships they do have. As is Cumberbatch's Sherlock.