Leonardo DiCaprio apologizes as he reaches for an e-cigarette; he’s spent a long day taking photos and doing interviews, and has been longing for a break. As he relaxes in a suite at the Four Seasons Hotel, he stops to admire the setting Los Angeles sun and offers a simple tribute: “Wow, that’s gorgeous.”

There is something cinematic about the handsome actor against the backdrop of the sunset, and something egalitarian about one of the biggest stars in the world being moved by a simple act of nature. Though he has specialized in larger-than-life characters in recent films like “The Wolf of Wall Street” and “The Great Gatsby,” DiCaprio comes off as remarkably down to earth.

“When I started acting, I didn’t think of it as a career,” DiCaprio, 39, says of his early start as a pre-teen appearing in commercials. “I always thought Hollywood was this magical world where a fairy came down and said, ‘Come live with the Munchkins; you are now one of us.’ ” He laughs. “I didn’t understand the concept of it as a career. I thought I would save up enough money to go to college.”

DiCaprio’s parents divorced when he was a year old, and he lived primarily with his mother, Irmelin, in a hardscrabble neighborhood he affectionately refers to as “Prostitution Alley,” near Western Avenue and Hollywood Boulevard. “I saw all the moral decay you could, beginning at 2 years old,” he notes. “But I also got to see how the other half lived.” That was thanks to a to scholarship to University Elementary School, a magnet program of UCLA, in the tony Westwood section of Los Angeles. His mother would drive him 45 minutes to school and back every day. “I could see that this other world was out there. And if I could only get my shot, I would never waste the opportunity. That mentality and that gratitude are still in me.”

Because DiCaprio is a star, it can be easy to forget he’s also an accomplished actor. It’s been 20 years since he landed his first Oscar nomination, at the age of 19, for his stirring performance as an autistic teenager in “What’s Eating Gilbert Grape.” Though he became an international superstar with “Titanic” in 1997, he has mostly eschewed heartthrob roles in favor of character parts and the opportunity to work with great directors.

At the top of that list is Martin Scorsese, who calls DiCaprio one of the hardest working actors he’s ever directed. They’ve made five films together, beginning with 2002’s “Gangs of New York,” and the partnership has paid off for both men. DiCaprio brought his long-gestating Howard Hughes biopic, “The Aviator,” to life with Scorsese at the helm; Scorsese finally landed an Academy Award for directing the 2006 crime drama “The Departed.” Their latest collaboration, “The Wolf of Wall Street,” has earned each of them dual Oscar nominations: Both received bids as producers, plus Scorsese scored a director nom, DiCaprio his fourth acting nom.

Though DiCaprio faces stiff competition for best actor, the perf might just be the one that finally wins the elusive statue for the thesp, who’s being critically lauded for capturing the pure raging id of real-life stockbroker Jordan Belfort. There is nothing his character won’t snort, and no one he won’t sleep with, and the actor strikes a remarkable balance between high-stakes drama and raucous comedy. It’s a challenging role he spent years attempting to bring to the bigscreen, and then fearlessly threw himself into — quite literally. One infamous scene that finds Belfort in a Quaalude-induced haze sent the actor to a chiropractor after he spent days writhing around on the floor during shooting.

While many actors half as famous would have hesitated to play a figure as inherently unlikable as Belfort — surely most would have winced at the prospect of the scene in which he sports a lit candle in his rectum — DiCaprio didn’t flinch. The movie has proved controversial, with some arguing it glorifies abhorrent behavior. “We knew we were doing a movie about incredibly distasteful people, and their likability would be questioned,” DiCaprio acknowledges. “But Marty said, ‘I’ve done a lot of movies like this, and I find that if you’re authentic in your portrayal of their nature and don’t try to give them a false sense of motivation, audiences will go along with you on the journey.’ ”

The hard part for the actor has been promoting the film. Notoriously private, DiCaprio has been opening up lately, relentlessly stumping for “Wolf,” and even going so far as to appear on “Saturday Night Live.” “I really wanted this movie to succeed, because to me, you don’t see R-rated films like this getting made that aren’t on an epic scale,” he says. “So I’m glad this film is now in the green. Studios ultimately look at what works and what doesn’t, and greenlight the things that do.”

In fact, “The Wolf of Wall Street,” like the majority of Oscar-nominated films this year, was not bankrolled by a studio but rather independent financiers (Red Granite), with Paramount responsible for its distribution and marketing in the U.S. and Japan.

DiCaprio, who shot “Wolf” after finishing Baz Luhrmann’s “Gatsby” and Quentin Tarantino’s “Django Unchained,” hasn’t yet made another film. He’s been focusing on his environmental work, including an auction for the 11th Hour, a wildlife charity tied to the 2007 documentary film he narrated. The event raised more than $38 million. It was just announced he will reteam with “Wolf” co-star Jonah Hill to star in an adaptation of Marie Brenner’s 1997 Vanity Fair article “The Ballad of Richard Jewell.” But for now he’s enjoying something he’s rarely experienced in the past 20 years as an actor: unemployment.

When DiCaprio began auditioning around the age of 12, the environment was cutthroat, he recalls. “Kids would try to intimidate each other, stare each other down — say, ‘Man, don’t even go in, I already got the job,’ ” he recalls with a laugh. “But through the process, I also met some of my best friends in the world.”

That includes actor Tobey Maguire, with whom he recently starred in “Gatsby.” Maguire says even at a young age, DiCaprio’s talent was obvious. “I went on one movie audition and I said, ‘I know who you guys are going to end up hiring. This kid named Leonardo DiCaprio,’ ” Maguire recalls. “He hadn’t even read yet, but sure enough, he ended up getting that role.”

The film, the 1991 sci-fi horror comedy “Critters 3,” marked DiCaprio’s first movie gig. That same year, he landed a part on the TV series “Growing Pains,” which he says was a crash course in being on a set. But it was his next film, 1993’s “This Boy’s Life,” based on Tobias Wolff’s memoir of growing up with an abusive stepfather, that would truly set his career on its course.

“It was the coveted role for every boy in his teens,” DiCaprio recalls. “You would be starring opposite Robert De Niro.” Even at the age of 14, he knew who De Niro was — his father George had taken him to see “Midnight Run” when Leo was 9. “He said, ‘You want to be an actor; you want to know what a great actor is?’ ” recalls DiCaprio. “He took me to the movie and said, ‘This is a great actor.’ ”

To prepare for the part of Wolff, DiCaprio immersed himself in cinema history, watching films from the 1950s through the ’70s. “That was when I began to understand that with acting — what’s the quote? ‘We stand on the shoulders of giants?’ I saw what had been accomplished before me and I just went, ‘Holy shit.’ ”

Director Michael Caton-Jones auditioned more than 400 boys for the role before narrowing it down to a handful, which included DiCaprio and Maguire. And he knew how essential the right actor was. “I knew that the film would either work or fail because of the kid,” Caton-Jones notes. “Once I’d made up my mind on Leonardo, I loaded the dice.”

Caton-Jones called DiCaprio back in and said his tape had been messed up and needed to be redone. “I worked Leo hard, corrected him, retook duff performances, fine-tuned his body language over and over again until what was on tape was the best reading we could have,” he reveals. “I then got a couple of the crappiest auditions from other boys I could find and put them together on a video for Art Linson, the producer, and said, ‘These are the three best kids we’ve seen. I know who I like, but what do you think?’ ”

DiCaprio eventually screen-tested with De Niro, performing a scene where the older actor has to shove a mustard jar in his eye. DiCaprio responded by screaming at his hero. “It wasn’t in the script; it was improvised,” he recalls. “I remember people laughing in the room. I didn’t know if I had messed up or if they liked it. But they gave me a shot.”

Maguire was also cast in the film, and recalls being shocked when they shot their first scene together, in which DiCaprio’s character tells his friends they are going to be stuck in the small town. “I remember watching him in this scene, and it was the first moment I went, ‘Holy shit,’ ” says Maguire. “I mean, he was so connected and rich and full of feeling. It was the first moment I went, ‘There is something serious going on here.’ ”

DiCaprio calls “This Boy’s Life” a seminal experience — he seemingly remembers everything about making the movie. But it was his next film that really solidified where he wanted to go as an actor. He was offered “more money than I ever dreamed of” to take a role in the Disney family film “Hocus Pocus.” But he decided he wanted to hold out for a small indie for which he hadn’t even auditioned yet, “What’s Eating Gilbert Grape.”

“I don’t know where the hell I got the nerve,” he says now. “You live in an environment where you’re influenced by people telling you to make a lot of money and strike while the iron’s hot. But if there’s one thing I’m very proud of, it’s being a young man who was sticking to my guns.”

For the audition to play the autistic Arnie, younger brother to Johnny Depp’s title character, DiCaprio was given a tape of a real-life child with a similar disability. “I watched it for three days straight, all day long,” he recalls. After landing the job — despite director Lasse Hallstrom’s initial concerns that he was too attractive — he spent a week at a center for special-needs children in Austin. “There were a hundred things I noticed and picked up on, and came to Lasse with a checklist of attributes for the character,” DiCaprio recalls. One included a habit of gesticulating with his fingers, which Hallstrom incorporated into Arnie. “He just said, ‘Okay, kid, go for it.’ ”

DiCaprio’s remarkable, sensitive performance made Hollywood take notice. He continued to build credibility with risky ventures, playing gay French poet Arthur Rimbaud in “Total Eclipse” and a drug addict in “The Basketball Diaries,” while his work in Luhrmann’s “Romeo + Juliet” helped his rising stardom. And then, in 1997, “Titanic” sealed it.

DiCaprio knows that many define his career as pre- and post-“Titanic.” But he says it was long before the megahit that he had formulated his own ideas about fame. “When I was 14, I was on the cover of Bop and Tiger Beat. Every two months, I would see a new kid’s face, and I remember saying, ‘This is not something that lasts very long.’ ”

He credits his career longevity partially to family and friends, whom he says have kept him grounded. Luhrmann tells of flying DiCaprio to Queensland to workshop “Romeo + Juliet” and adds, “Leonardo, being Leonardo, he cashed in his business class ticket and flew himself and his friends coach to Australia.” He’s intensely loyal to his business partners: He’s had the same manager, Rick Yorn, for more than 20 years.

DiCaprio also has never given up his commitment to improve. For “The Aviator,” he enlisted acting coach Larry Moss to help him, and still consults with him regularly. “He’s a more than an acting coach,” the thesp says. “He’s somebody who really makes you talk about your life, reflect upon it, and grow.”

In addition, DiCaprio schooled himself in the classics. He was “blown away” by the vulnerability of James Dean in “East of Eden” and “stunned” by the power of Montgomery Clift. It was that knowledge and respect he credits with guiding him away from traditional leading man roles and to pursue work that has compelled him.

Sometimes, however, the compelling collides with the traditional; though he was hesitant about signing onto “The Great Gatsby” because of the emphasis on the character’s handsomeness, he ultimately couldn’t get the story out of his mind. “That’s one of the most elusive, existential characters I’ve ever read,” he muses. “The mystery of Gatsby is still something that eludes me, even now.” It eluded critics, too, who were more disparaging of the film than of the performance of DiCaprio, who helped the movie mint $351 million worldwide.

Scorsese can attest to the actor’s commitment; he had met with DiCaprio after “Gilbert Grape” and they talked about working on something together. “Then, he made ‘Titanic,’ and suddenly he was a superstar,” Scorsese recalls. “In the back of my mind, I thought, Will we have the chance to work together now? Because that kind of massively popular star status changes people, particularly when it happens so suddenly. I’ve seen it happen many times.”

Then Scorsese had the opportunity to make “Gangs of New York,” a film he’d spent 10 years developing. “And there was Leo,” says the director. “When we met, I realized immediately he’s an actor first and foremost, and when he’s making a movie, he checks the stardom at the door. I was so impressed by his dedication and commitment, his willingness to try anything, and — this is important — to collaborate. Leo will try anything. He’ll do whatever it takes to find a measure of truth in the character.”

Maguire talks of how DiCaprio would walk around for months with the books “The Great Gatsby” and its precursor “Trimalchio,” comparing scenes in each Fitzgerald book to the film’s script. “He was constantly breaking down the intentions of Fitzgerald in the different versions and asking if we should explore this or that, constantly mining it and seeing if we could make it better somehow,” Maguire says.

Echoes Luhrmann, “His tenacity in overturning every stone in the pursuit of understanding a character is undiminished. Simply said, prepare yourself for sessions that go to two or three in the morning on a shooting night.”

Such commitment has inevitably lead DiCaprio to producing as well, though he concedes, “To tell you the truth, my producer cap is a very selfish one. On the road to finding material for myself, we accumulate other things that are interesting.”

His production company, Appian Way, has been responsible for such DiCaprio vehicles as “The Aviator” and “The Wolf of Wall Street,” but also films like “Out of the Furnace” and “Red Riding Hood” in which he didn’t appear. He admits he’s involved in every aspect of the pictures he stars in — from convincing Scorsese to direct “Wolf” to working for years on the script with Terence Winter. But on most of the projects in which he doesn’t appear, his involvement is limited mainly to the development process. “I’m very active in putting a team together, deciding what the focus of the story should be. Because if the right people aren’t chosen from the start, a great idea can turn out very different,” he notes. “But once you give it over to a filmmaker, you have to allow them to do their thing.”

Off all the film and TV projects Appian has in the works, DiCaprio seems most enthusiastic about the adaptation of Erik Larson’s true tale “The Devil in the White City: Murder, Magic, and Madness at the Fair That Changed America,” in which the actor would play serial killer H.H. Holmes. “We have a script for that. We’re doing our last couple rewrites, but it’s amazing,” he enthuses. “I want to be in that one. That one is very real.”

At this point in his career, it’s hard to believe there is any role DiCaprio couldn’t get, but he reveals this isn’t true. Years earlier, he met with Luhrmann about the role in “Moulin Rouge!” that eventually went to Ewan McGregor. “To be honest, I’m not really prepared to do a musical, simply because I think I have a pretty atrocious voice,” he notes. “But we had a friendly thing where it was me and him and a piano player, and we tried to sing a song together. It didn’t go too well. I think it was ‘Lean on Me,’ and when I hit the high note, he just turned to me.” At this point, DiCaprio affects Luhrmann’s Australian accent, “ ‘Yes, D, I don’t know if this conversation should continue.’ ”

With that, DiCaprio dissolves into laughter. “The truth is,” he says, “I honestly feel just so lucky to make movies.”