Until almost the end of 2008, British actor Bill Nighy was one of those faces you couldn’t put a name to.

In his 50s, Nighy hails from the southern outskirts of London, where his father managed a garage in the bleak satellite town of Croydon and his mother was a psychiatric nurse. Bill’s life partner is actress Diana Quick, who, though not as big a star, is perhaps more recognizable than he. Bill had asked Diana to marry him, but she declined the institution if not the man.

“I do quite nicely in Britain,” states Nighy, to whom Hollywood has paid infrequent attention until recently.

“You can be a working actor here,” he explains, as one who plies his trade in various media, not just movies.

As for being a middle-aged actor, “It’s far from catastrophic. There is always a need for actors to portray the usual male authority figures,” he says.

And Nighy himself is certainly evidence of that in the rather offbeat epic “Valkyrie,” based on — but not scrupulously so (according to historians and critics) — a real-life attempt to assassinate Nazi Germany’s dictator Adolf Hitler.

The film stars, improbably, Tom Cruise as Hitler’s intended assassin, with his American accent and a height that belies the Nazi penchant for taller, if not always blond, officers. The media has widely criticized the casting of Cruise — with one Los Angeles paper saying he might as well have played Hitler — but without his involvement (and box-office draw) the film might never have been made.

Another big wheel moving “Valkyrie” (code name of the plot to assassinate Hitler) toward motion-picture fruition was director Bryan Singer, who has helmed many major box-office projects, including the latest “Superman” picture.

Nighy won’t comment much on Cruise in the role, but notes, “Taking the role required courage, because the world would be watching and waiting. Whenever something is historically inspired, there is going to be more of a spotlight and more room for criticism.

“Bryan has done a wonderful job of re-creating atmosphere as well as incredible suspense. What makes it all the more incredible is the fact that we know how it turns out. We know that all the assassination plots against Hitler failed, that he survived until the end of the war, and only then took his own life.

“He waited until he had all but destroyed Germany before abdicating his insane and evil dream, or nightmare.

“Yet even knowing the outcome, this film is almost unrelentingly suspenseful.”

Cruise portrays Col. Claus von Stauffenberg, the German officer heading the plot. In real life, Stauffenberg had lost, due to battle injuries, a hand, some fingers, and an eye, necessitating the eye patch we see on screen. Kenneth Branagh is a costar, and like Nighy doesn’t attempt a German accent; most of the Germans sound — like imperial Romans in old movies — English.

But Nighy’s feeling is that, “The story carries the audience along. Hopefully, the actors embody the characters they’re playing well enough that most audience members aren’t constantly aware of accents and such. After all, this is not a documentary. It is a sort of adventure film, certainly a suspense film.

“But many people don’t know that there were upper-echelon Germans who wanted to get rid of Hitler, who saw his madness and the destruction he was wreaking on his people.”

One does wonder whether the German officers are meant to be seen as heroes simply because they oppose Hitler, as that didn’t mean they were necessarily fair-minded, or not anti-British or not anti-Semitic, or anything like that.

“You have to view the film,” offers Nighy, “then draw your own conclusions.” He admits that some who opposed Hitler did so primarily because they wanted power for themselves.

“This project was cast very carefully, which shows in the result . . . the different sorts of men, their personalities, conflicts and the doubts some of them have. The film is also a character study, quite an intriguing one. My character is one of the most riveting I’ve ever played.”

Nighy’s character — Gen. Friedrich Olbricht — is a military hero charged with the responsibility of setting Operation Valkyrie in motion. His character is largely sympathetic, though his hesitation in carrying out his anti-Hitler duties provides a major plot (and historical) element.

Singer, the director, and others behind the scenes have said that Nighy was cast as Olbricht because of the actor’s likability, which was necessary to counterbalance Olbricht’s wavering role.

Friend and costar Dame Judi Dench, with whom Nighy worked in “Notes on a Scandal,” told the Los Angeles Weekly newspaper, “Bill’s an actor. He’s so very present in a given role. He’s so focused and so earnest. But whatever he plays, he brings a sense of humanity to it. He would not be the ideal for an out-and-out villain, at least I don’t think so.”

Nighy’s work in such films as “Notes on a Scandal,” “Love, Actually,” and “The Constant Gardener” have made him increasingly recognizable to international film-going audiences.

But when approached about “Valkyrie,” was Nighy at all hesitant, in view of it having an American director and an American star?

“I was, shall we say, intrigued and a bit doubtful. Not about Bryan Singer or Tom Cruise, nor did I have qualms about the Hollywood aspect of the picture. There have been times when Hollywood screws up royally on history, including a film that shall go unnamed which turned British (World War II) heroes into American ones. But when it comes to this era, . . . well, who could top Hollywood’s and Mr. Spielberg’s ‘Schindler’s List’ — to name one?”

Rather than fretting over the Hollywood factor, the actor was initially unsure about the character — only later deciding that the man had to act the way he did because of who he was and the historical situation.

“The filmmakers said they didn’t see Olbricht as ‘the fall guy’ or want to present him that way, and I, after learning quite a bit about him and about Operation Valkyrie, thought we should do well by the man, give him his dignity. He was not a weak man, but what happened . . . well, it happened, and you’ll have to see the movie.”

Nighy was surprised to learn how much opposition there was at the heart of the Third Reich to Hitler, but as he points out, opposition is one thing, action another.

Like most people, he didn’t realize the extent to which Hitler, initially voted into power — had made himself into a national deity.

“In Hitler’s Germany, and I do mean ‘Hitler’s Germany,’ for that is what it became, for the duration, citizens swore an oath of allegiance not to the nation, but to the Fuhrer. He was actually placed before, and above, Germany.

“So how could there not have been opposition, especially once it became clear that he was steering a course of destruction for the nation? No, I’m quite amazed, still, to have been chosen to be a part of this incredible project.”

The picture was shot in Germany, sometimes on the actual sites where the historical events occurred. The grimness of the topics and of his role was relatively new to Nighy, who was used to playing lighter parts.

“Well, people see you the way they see you,” he conceded. “To a large extent, it’s out of your control. But being in ‘Valkyrie,’ I think that will allow people — including, of course, producers and casting directors — to see me in another light, too.”

But as his motion picture profile and stock rises, would Nighy ever consider giving up live theater?

“Not on your life. No!”

Nor probably would he give up television, having done significant TV work on both sides of the Atlantic over the years. He won a Golden Globe Award from the Hollywood Foreign Press Association for “Best Actor in a Mini-Series” in HBO’s “The Girl in the Cafe.” In Britain, too, he’s won numerous awards, including two of the so-called British Oscars (BAFTAs) for television and for film work. Might Nighy pack his bags and decamp for Hollywood anytime soon?

“No, and the wonderful thing is there’s really no need for that. When it comes to starring in motion pictures, well, Americans have more of a lock on it than ever before. Where once, long ago, you had David Niven, Deborah Kerr, numerous British film stars working in Hollywood — starring in Hollywood — today there aren’t many Brits at the top of that list.

“But, I’m proud to say, when it comes to casting key supporting or costarring roles, parts that require a degree of experience and technique — and yes, talent — well, Hollywood casting directors and filmmakers know where to look. They look to Great Britain.”

Possibly Nighy’s best-known role internationally is as the pirate captain Davy Jones in two of the “Pirates of the Caribbean” movies. For Nighy, though, such high-profile Hollywood forays into “foreign” territory are by no means over yet.

That’s because, in October, 2009, Columbia Pictures (a unit of Sony Entertainment) will release the movie version of Japan’s boy hero, Astroboy, in what’s currently titled “Metro City.”

A reported combination of animation and live action, the film will feature Freddie Highmore as the voice of Astroboy, who debuted in a 1951 comic strip by “father of manga” Osamu Tezuka. Then, in 1963, a Japanese TV cartoon version enjoyed international success, and Astroboy was brought back in the 1980s — by then as an anime (Japanese animation) icon — and also in 2003.

After that, Sony paid a hefty fee for the right to make a film of the story of the boy robot who was created to replace a scientist’s son who was killed in a car accident. Like any comic strip superhero, Astroboy spends his time fighting bad guys, mostly other robots and also aliens from outer space.

How did Nighy get involved in this unusual project?

“Sometimes I ask myself the same question. You absolutely cannot plan your career in the movies. If you try, you’ll be constantly frustrated. But every now and then, someone comes knocking on your door, not literally, but you receive an offer for a project — the Astroboy, ‘Valkyrie’ — and you have to wonder. And you’re thankful, because it turns out to be something rather stupendous.”

However, the actor is barred, along with the rest of the cast, from giving away hardly anything about the Astroboy project. But he did say: “This film isn’t just for children, although most of them will be delighted by it. I think adults will have a very good time watching this, according to what I’ve seen of it, whether or not they view it with a child in attendance.”

Nighy continues talking up “Valkyrie,” whose impressive cast also includes Tom Wilkinson, Terence Stamp and Eddie Izzard. He adds, “An actor’s work is often illuminating to himself, though often it just illuminates something about himself. In this case, going to Germany and, before that, learning so much about the assassination plot, I learned a lot. Not just about history, which is of course important, because we know that all too often it can repeat itself, but about human beings. What they are capable of, how they react, and why.

“But then, on top of this huge dollop of knowledge and experience that I as an actor was granted, to be able to share this with audiences around the world, . . . it’s, well, it is awesome.

“The project is one of mammoth scope, and it’s a topic I don’t think we can ignore. And I think Bryan (Singer, producer as well as director) has capped his already impressive career with this.

“It is a film,” he concludes slowly, “with ambiguities. It is not black and white. And I think the films that aren’t black and white, that leave room for thought, and from which you can learn something as well as be mightily entertained, are better than those that just have ‘the good guy,’ and which virtually tell you how to react and how to think.

“But the point is experiencing it for yourself. Without having to read a history book, to be able to visually almost participate in this very tense and suspenseful part of not-so-long-ago history. It is grade-A entertainment, but it’s more than entertainment. . . . You don’t have to be a Tom Cruise fan to enjoy this or have an unforgettable experience, though of course that wouldn’t hurt.

“The lad is quite charismatic, and this may be the bravest thing he has done on screen.”