In a Broadway season long on luscious leading men — Orlando Bloom, Daniel Craig, Zachary Quinto, Ethan Hawke — Brian J. Smith’s a standout.

His fans knew that long before he hit the stage. Google him, and one of the first things to pop up is “shirtless.” And there he is on YouTube, in a scene from the 2005 flick “Hate Crimes,” looking all buff and bare-chested.

“Damn sexy,” says one post. “So damn hot!” says another.

Turns out, he’s just as hot in a shirt, tie and suspenders.

Director John Tiffany’s stage revival of “The Glass Menagerie” has generated buzz since it opened in Boston last spring. But, primed as we were to cheer its stars — Quinto and Cherry Jones as Tom and Amanda, Tennessee Williams’ conflicted son and his mother — we didn’t expect to be bowled over by . . . Jim, the Gentleman Caller.

It’s a small role — just one scene in Act 2 — but Smith radiates such all-American decency that The Post’s Elisabeth Vincentelli called his performance “the most powerful in the show.”

This isn’t Smith’s first turn on Broadway. In last year’s “The Columnist,” he tumbled out of John Lithgow’s bed in his underwear. He’s also done TV shows like “Defiance,” whose executive producer, Kevin Murphy, hails him as the leading hottie in a series “replete with aesthetically pleasing menfolk.” Maybe you’ve seen him, too, as futuristic GI Joe Lt. Matthew Scott in “Stargate Universe.”

Brian J. Smith (above, with Celia Keenan-Bolger) is turning heads in a single, stunning scene in “The Glass Menagerie.”

Which is ironic, considering Smith’s Plan B. As he tells The Post, “I almost joined the Army!”

That was six years ago when, fresh out of Juilliard, he found himself bartending and desperate.

“I was two months behind in the rent, I didn’t have insurance and I’d just auditioned for [a role] and was told they went with somebody else,” says Smith, who’s 32 and lives in Harlem. “I figured, it’s a sign! I went to the recruitment office on West 72nd Street and was going to show up the next morning at 8 for a physical.”

Luckily, he called his agent first. “He screamed, ‘What!? You can’t do that — you have to be in New Mexico next month. The other guy passed and the role is yours!’ ”

It was a win-win situation: Not only was Smith warmly reviewed in that film, 2009’s “The War Boys,” but he swears our national security is safer for his not signing up.

“I’d make a terrible soldier,” he says, laughing. “If that part hadn’t come through, I don’t know what my life would have been like!”

For starters, he wouldn’t be chatting over lobster rolls at Al Pacino’s table at Joe Allen.

“I look at the roles I’ve played — heroic, very masculine American guys — and it’s me playing out a fantasy,” says the six-footer. “I try to be that boy I idolized in high school.”

In the land of “Friday Night Lights” — small-town Texas — Smith was the kid who failed at sports, “the one off doing cartwheels and chasing butterflies during soccer.” His construction-worker father and his mom weren’t quite sure what to make of him, but Smith says they never made him feel ashamed for being different.

He found his niche in theater, first in high school and then at community college, where he met future “Ugly Betty” star Michael Urie when they co-starred in “Titus Andronicus.” Urie steered him to Juilliard.

Along the way, Smith started working out — strenuously — to morph into the kind of guy you’d see on the field, both in battle and football.

Several shirtless roles followed, but the workouts took their toll. “It destroyed my body,” he says. “Your muscles get so tight and so big, I couldn’t touch my toes.” These days he does yoga, with a dash of weight training.

You don’t need big muscles to play the Gentleman Caller, a role Smith says is so beautifully written, “you can read it standing on your head wearing a tutu, and that scene is still going to move people!”

Cherry Jones insists the credit lies with him.

“I just worship and adore that boy,” she says. “He’s kind and he has great compassion, which is why he’s such a wonderful actor.”

Michael Nankin agrees. Three years ago, he directed Smith in a TV movie, Syfy’s “Red Faction: Origins,” and calls him a “total pro.”

“We spent two months in Bulgaria shooting this movie under the worst conditions — frozen bathrooms, hideous food — and Brian not only delivered a marvelous performance but took his responsibility as No. 1 on the call sheet to keep everyone’s morale together,” Nankin says. “He has this amazing, can-do attitude. He’s a Texas boy who made it big on Broadway — it’s an incredible story.”

Smith says he’s game for anything.

“If I got anything, I’ve got grit,” he says, sipping a Diet Coke. “I can take ‘no’ a lot. It would discourage me but I’ll still keep going . . .

“Until,” he laughs, “I join the Army!”