Billy Bob Thornton, the beating heart beneath the positively profane ‘Bad Santa 2’

You shouldn’t care about Billy Bob Thornton’s opinion. Not because he doesn’t have one, but because the actor isn’t sure what makes his thoughts any more significant than the next guy’s. Thornton, 61, tends to underestimate himself, though. In fact, he’s made a career of playing underestimated men and they’re always more than what they seem at the outset. If you ask him to reflect back and glance over his film career, which launched in the mid-’80s with a bit part on “Matlock,” that’s exactly what he sees as the through-line.

“I like playing people who on the surface look like one thing but on the inside they might be something else,” Thornton says, sitting in a desk chair in a hotel room at the Four Seasons Beverly Hills. He’s wearing sunglasses, although they might actually be transition lens that are mistaking the dark room for a sunny exterior. The actor has paused on a series of drawings of faces he’s been making on the hotel notepad to discuss his work, most notably in the long-awaited sequel “Bad Santa 2.”

“My characters might know more than you think they do,” Thornton continues, pen still in his hand. “Like the character I played in ‘A Simple Plan,’ who really was the heart and soul of the movie and yet he looks like the idiot on the surface. I’ve played a lot of characters from the underbelly of life who either want to be or really are more than they appear to be.”

What draws him to these types of men specifically? “Maybe I feel that way sometimes,” the actor says. “I have a lot of insecurity as a person, so I think I’d be too afraid to play somebody who is supposed to be perfect and amazing and beautiful. I’d probably screw it up. I never wanted to play those characters. If you do the story of Wyatt Earp, the part you want to play is Doc Holliday, not Wyatt Earp.”

That may be what brought Thornton back to the foul-mouthed, St. Nick costume-wearing Willie in “Bad Santa 2” (see the attached trailer, which contains graphic language). The first film made a robust $76 million worldwide when it was released in 2003, surprising viewers with its crass story about an alcoholic who partners with a con artist, played by Tony Cox, to rip off shopping outlets posing as a mall Santa and his elf. It was dirty, fun and showcased Thornton as a different sort of character than we’d seen in the past. After the film hit theaters, all Hollywood wanted from him was to play more of the same.

“Believe me, they were offered to me,” he says. “Every time they wanted [a jerk] they called me. But I think we tried to handle it well. I haven’t really done one kind of like that since.”

Instead, Thornton has spent the past decade-plus chasing work he could feel passion for: FX’s “Fargo” and Amazon’s David E. Kelley-helmed “Goliath” on TV, and films like “Our Brand Is Crisis” and “The Judge.”

A sequel to “Bad Santa” was always inevitable, but there was a question of when. The studio changed hands several times and red tape bogged down the production. There were several versions of the scripts written and for Thornton it was important that he, Cox and Brett Kelly, who plays Thurman, take equal hand in the story line. “People want to see the three of us, not just me,” Thornton notes, adamantly. “I don’t think it would have been as appealing to the audience without those three characters.”

Thornton is wary of critical response to “Bad Santa 2” because he thinks it’s easy to write off a comedy sequel. The follow-up isn’t always as good as the original, but in Thornton’s view, this film should be judged on its own merit. He believes that the sizable gap between the two actually made this a better film (although it’s just as crass and ridiculous as the first one, evidenced by the fact that director Mark Waters gave Thornton a set of prosthetic testicles as a wrap gift).

“In a lot of ways I think that helped because there is enough separation,” Thornton says. “Now you’re looking at another movie in a different time and yet we wanted to keep the spirit of the first one and elevate it somehow in subtle ways. I think one of the problems in comedy sequels sometimes is that people will make the sequel right away to capitalize on the success of the first one like, ‘That was a hit so let’s just get another one out.’ In a sense the second one is more of a Christmas movie because it’s got more of a story arc and more of a character arc. The 13 years, I think, did us some good.”

The actor already has an idea for a third “Bad Santa,” although that’s not an inevitability until the box-office numbers come in. Thornton, who has written and directed several films, including “Sling Blade” and “All the Pretty Horses,” won’t be the one to write it, though. He’s done with that. Or, rather, Hollywood is done with him doing that.

“There’s a million stories left in me to tell,” he admits. “That’s not the problem. I’m not opposed to directing and writing. I think the audience is opposed to me doing it. I don’t think what I have to say as a writer or a director are relevant now. I think I’m obsolete as a writer and director. I was influenced by Southern novelists. That’s really what I’ve always written and directed. I just don’t think that’s exactly what [the studios] want.”

Maybe he’d write a novel, but that sounds like a lot of work, and Thornton suffers from dyslexia and obsessive compulsive disorder so reading and writing can be tough. He’s still writing songs, which he did before he started acting, and his band the Boxmasters will release a new album next year that they wrote to sound like it was recorded in 1966. He doesn’t have Twitter. Well, he does, but someone from the record label runs that and Thornton isn’t at all interested. He doesn’t get why people expect so much from celebrities and why they put him on a pedestal just because he gets up in the morning and sometimes goes to a movie set.

“Look, I’m a guy who grew up in Arkansas and Texas,” Thornton says. “I used to run a backhoe and worked at a sawmill and in a machine shop and played in a rock ’n’ roll band. That’s what I did growing up. I played baseball. I’m just a guy who happens to be an actor and I use my life experience and put it into my roles. So, to value my opinion any more than anyone else’s? I’m not saying my opinion isn’t valuable. But my opinion is no more valuable than a plumber over in Encino. I’m just another guy who works at something.”

Thornton pauses, fiddling with his pen. He grins. “So,” he says, “if you’re going to ask me my opinion, go ask Chuck the plumber. See what Chuck thinks.”