Meet Billy Bartley, the big cheese at world-famous Mr. Bartley’s Burger Cottage in Harvard Square.

Harvard presidents may come and go, but Bartley is anything but retiring. Most days, you’ll find him behind the perpetually sizzling grill. He carries himself like an overly caffeinated Marine Corps drill sergeant — but with a sense of humor.

Bartley's father opened the business as a convenience store called the Harvard Spa more than 50 years ago. Then Billy was born.

"Realizing what a money drain I’d be, I think he decided he’d better up the ante and turned it into a restaurant,” said Billy. He chuckled and added, “just in bail money alone, he projected, 'this kid is going to cost me a fortune.'”

On the job, Bartley has a uniform: a pair of dad jeans topped by a green Bartley’s t-shirt.

“I was in a playpen out back when I was less than a year old, grabbing straws out of waitresses’ aprons,” Bartley said. “When I was 13, I was working the grill.”

Bartley still works the grill, and he moves with the fluid determination of a welterweight boxer. The essence of muscle memory, he personifies multi-tasking. The Burger Cottage is sweat equity in action.

It’s not a pretty room, although it does have character. Energy defines the space. Posters of Johnny Cash and Elvis – to name just two – populate the walls. A huge banner reads: “The Wall Street Journal Voted Us One Of The Best Burgers In The USA.” A riot of artifacts, street signs and sports memorabilia anchor the vibe.

When asked what his favorite piece of decoration was, he pointed to a piece of sheet metal a bit smaller than a no-parking sign: “Check this out. I hung it over the condiments because that was the only open space. ‘Practice Safe Lunch, Use Condiments.’”

It’s a classic morsel of hamburger humor.

Bartley’s Burger Cottage sits between two other landmarks, the Hong Kong and the Harvard Bookstore. Harvard University is the landlord.

“They have always been really, really good to us,” Bartley said. “They show great respect for us, too. We don’t want to change and they don’t want us to change. So it works out perfect.”

Not to put too fine a point on it, Bartley is a power broker.

“Senators, governors, they literally come in here and kiss my ring,” said Bartley. “And the second I stop doing this, it’s over. I have a platform, and I know how to use it.”

His platform is his menu. Dozens of burgers and a handful of sandwiches carry special tags lampooning — or celebrating — the powerful and the famous: “The Mike Pence, Way Right And Way Wrong”; “The Tom Brady, Triumphant”; “The Caitlyn Jenner, You Go Girl”; “The Beyoncé, Hot”; and “The Legalize It, Now Tax The Hell Out Of It.”

His most recent creation?

“The Cabinet Millionaires Club — sausage, peppers, onions, spicy mustard.”

When asked which burger he is most proud of, Bartley recalls one of the most controversial items to grace his menu: "The Iraqi Burger, Once You Attack It You Are Not Going To Want To Leave.”

“Everybody told me, 'no, no, no,'" said Bartley. But that didn't stop him. "Whenever anybody says no, that means yes, yes, yes to me.”

There is no deep secret about how you make it onto the menu. Bartley uses a time-tested formula — politics.

“Eliot Spitzer did it the good old-fashioned way,” he said. (Spitzer, of course, was the New York governor forced to resign for consorting with an escort.)

Bartley may enjoy his contributions to national debate, but it is local issues that he truly relishes: “I will tell you, there is no one more feared than I by the Cambridge City Council. If you cross me, you go on my menu. So sometimes you want to be there, sometimes you don’t,” he said.

Despite decades of great success, despite customers like Gov. Charlie Baker and Harvard’s Skip Gates, despite the amused affection of a dedicated staff, Bartley does have a fear. It took a second for him to come clean. With a straight face he said, “Fear of disappointing your entire family.”

And then the grin and the infectious laugh returned. “If you screw this up," he added, "you don’t get invited to Thanksgiving dinner.”

Bartley may be a merry prankster, but at heart he is a traditionalist. He practices his craft with the skill and fidelity of an artist. Meat is his medium — about 1,000 pounds of ground beef a week.

Correction: An earlier version of this article misstated Eliot Spitzer's job title when he resigned. The post has been updated to reflect that he was the governor.