He was The Rock. Now he’s a solid Dwayne Johnson.

Sure, there was the transitional Dwayne “The Rock” Johnson, but he doesn’t call himself by his wrestling moniker anymore.

Confidence is like that in the movie industry. Success breeds it, and the 38-year-old has enjoyed his fair share since the transition.

His latest Rock-less vehicle is a serious sort of revenge thriller called Faster, which opened on Wednesday.

In the shoot ’em up, directed by George Tillman Jr., Johnson plays Driver, an ex-con who sets out to avenge the murder of his brother after a screwed-up bank job. The trouble is that Driver hits some obstacles on his mission to pay back those who betrayed him.

A seasoned cop (Billy Bob Thornton), just days from retiring, is on his trail. And so is an oddball hitman (Oliver Jackson-Cohen), who kills more for kicks than bucks. Carla Gugino plays another cop trying to sort out the mess, while Tom Berenger shows up briefly as the warden offering advice that doesn’t get heeded.

As Driver gets deeper into the trackdown, he starts realizing he may have more enemies, and targets, than he had bargained for.

Dark and disturbing, Faster is a definite departure from Johnson’s previous string of comedies but, according to the actor, that’s a coincidence.

“It wasn’t necessarily important for me to go back and do a kick-ass movie,” he says during a recent Four Seasons Hotel interview in Beverly Hills, Calif. “If I see something I like, I am going to take a shot at it.”

Written by Tony and Joe Gayton, Faster’s sub-theme of family loyalty attracted Johnson to the project as much as the action did. “I would go to the end of the Earth to protect my family,” he says.

Extra effort was required on other fronts. He bulked up for the part, lifting weights for three months “to put on about 10 or 12 pounds of muscle.” He adds with grin: “Because bigger is always better.”

And, in order to convincingly portray “the wheel man for the bank job,” he spent a few weeks before filming started learning how to stunt drive at Rick Seaman’s Stunt Driving School.

“I thought it was important for me to be in those driving shots, so they wouldn’t have to cut away,” Johnson says, referring to Faster’s many car-chase sequences. “And it’s also the fun part of my job.”

Still, his portrayal is grim, defining one of his most violent characters so far. “I thought of him as a person who was tortured and in turmoil,” the actor says. “But he finds out revenge only brings more pain.”

Unlike most tough guys in the movies, Johnson has had epic smackdowns, real and choreographed.

He was a starting defensive lineman with the University of Miami Hurricanes, and then portrayed The Rock, the WWE all-star wrestling champion with the muscular look and the arched eyebrow the cameras loved.

Wisely, Johnson eased into acting. He had guest appearances on Star Trek: Voyager and That ’70s Show. His cinema debut came with a cameo in 2001’s The Mummy Returns, which led to the headliner role in The Scorpion King the next year.

Scathing reviews aside, he championed onward. By 2004, he quit wrestling to focus strictly on his movie career. He won some, lost some, but never gave up on his double focus of doing both comedies and dramas.

The action flick The Rundown worked, but the remake of Walking Tall didn’t. He received raves for his cameo as the gay bodyguard in the crime comedy Be Cool, but was skewered for his Sarge role in the sci-fi bomb, Doom. He was merely OK in Gridiron Gang.

Then, he committed himself to the comedy side — ditching The Rock name in the process — with more consistent success. He played the arrogant football star in the hit kids’ flick The Game Plan. He earned positive notices for his dim-witted and narcissistic Agent 23 in the retooling of Get Smart.

Roles in the mediocre Race to Witch Mountain and voice work in Planet 51 followed. But last summer, his spoofing cameo in Will Ferrell’s cop farce, The Other Guys, made up for the previous missteps.

Meanwhile, Johnson will mix it up again: He just wrapped Fast and Furious 5, in which he plays a U.S. special agent. And he’s about to start shooting the sequel to Journey to the Centre of the Earth called Journey 2: The Mysterious Island. He’s also on tap to play Sinbad in the fantasy adventure Arabian Nights.

“Action has always been my home,” he says. “But, 10 years ago, I didn’t want to be pigeonholed, and I still don’t.”