The big-money basketball question as the 15-time All Star hits town is how a career centerpiece will adapt to being a complementary part of a team replete with veteran stars. The man of many nicknames — Diesel, The Big Aristotle, Shaq Fu, The Big Cactus, Superman, Shaq Daddy, The Big Shamrock — is trying out something new with the Celtics. The Big Role Player. The Big Substitute. O’Neal understands that Boston will use his diminished skills in special situations.

“My mother told me, ‘You are so funny it’s either going to get you in trouble or make you a lot of money one day,’ ’’ said O’Neal.

And for him, that often means playing the comedian. He is a pretty funny guy, and he knows it.

“People see me as touchable and real,’’ said O’Neal. “I make them feel like I know that guy. You’ve got to be yourself. A lot of athletes make the mistake of trying to build their brand. I built my brand just by playing and being myself. People who have the most successful image live by what I live by. Image is reality. A lot of stuff I do, I’ve been doing since I’ve been 8-years-old.’’

O’Neal, 38, who signed a two-year, $2.8 million contract with the Celtics this month, brings to town a brand of sports celebrity rarely seen in these parts. He wears his colossal fame with remarkable ease. His persona, he says, is the natural byproduct of a never-ordinary life.

“It’s like this in every city, every country,’’ said O’Neal. “I read on the Internet that I’m the third most recognized face in the world.’’

Hardly anything stops the traffic chaos of the Square. But when Shaq dropped his formidable frame onto a bench, the crowd swarmed and traffic stopped.

He arrived without celebrity entourage — no publicist, no handlers, no burly security — and soon had a mob of students, tourists, and shoppers trailing in his vast wake. The growing crowd followed O’Neal from Widener Library through Harvard Yard to the Harvard Book Store, disbelieving what they saw. They directed cameras and shout-outs his way. Everyone wanted a piece of the 7-foot-1 megastar, and just about everyone got one.

The brainiest and most reflexively skeptical corner of the Hub simply swooned. And Boston’s newest Celtic took it all in stride — indeed, one giant stride after another.

Jolly, immense, amused, amusing, patient, thoughtful, and soon to be draped in green, O’Neal, the NBA’s most celebrated giant, took on Harvard Square yesterday.

CAMBRIDGE — He waited patiently with the horde for his Mr. Bartley’s burger. He amiably patted the bronze boot of John Harvard, bought two dry tomes at a bookstore, and paused to ask a clutch of students the one question on everyone’s mind yesterday.

“I’m much older now,’’ he said. “This team is good with or without me. Sometimes, in order to win, you have to sacrifice. I don’t mind sacrificing. At the end of the day, it’s all about winning.’’

“I’m going to do what I’m told to do. Whatever they need me to do. I’m not in a position to cause trouble or cause a ruckus. The reason why younger in my career I acted a fool is because they made me the CEO. If I’m the CEO and I’m getting all the blame, we’re going to start doing it my way.’’

But yesterday wasn’t about how he will fit into Boston, it was about how the city may change because he is here. Shaq, in town for last night’s Ultimate Fighting event at the TD Garden — he is a huge fan of the popular blood sport — was eager for an unfiltered sense of his new surroundings. And he quickly made it plain that he is open to almost any kind of encounter.

At one point early in the day, O’Neal let newlywed Kristin Schifone jump into his arms for a photo op at the Four Seasons Hotel. “Thank you,’’ said Schifone, who joked that her new married name was O’Neal. “You’re such a good sport.’’

Moments later, O’Neal was wrestling on stage at the UFC Fan Expo with 13-year-old Matt Weisman from Easton. “I’m like up to his waist,’’ said Weisman. “It was wicked fun.’’

Leaving the event, a pair of police officers asked O’Neal to pose for pictures.

“Make it look good,’’ said O’Neal.

The results are comic-book-worthy shots with one officer pretending to go after O’Neal with a billy club and another officer pinning him against a wall in a choke hold. O’Neal sells the humor with his over-the-top expressions. Once he gets a glimpse of the digital images, he cannot stop laughing.

“I’ve got my PSA right there: Don’t mess with the Boston police,’’ said O’Neal.

The range of interactions speak to O’Neal’s wide-ranging appeal and experience. He has recorded rap tracks with Jay-Z and challenged Rachel Ray to a cooking contest on his reality show “Shaq Vs.’’

He envisions a future episode of that show featuring Ray Allen, Kevin Garnett, Paul Pierce, and himself in a rowing contest on Charles River with the Harvard Crew Team. He can talk reverentially about Celtics legend Bill Russell and befriend teen pop star Justin Bieber. He talks about studying toward his PhD in Human Resource Development, working on a dissertation titled “The Duality of Humor and Aggression in Leadership Styles.’’

Of the topic, O’Neal said, “I’m anxious to see which leaders are more effective: the humorous ones or aggressive ones.’’ He hopes to interview President Obama and Steve Jobs for the project.

O’Neal, in short, is a man with plenty to preoccupy him and who doesn’t need to seek stardom anymore. He simply enters a scene and the galaxy finds him. He has more than 3 million followers on Twitter, has made it a cause to help police pursue Internet sex predators, aspires to run for sheriff one day, and mused yesterday about taking courses at Harvard Law.

And yet there seems a kind of humility, or at least of regal patience, about him. He said he still remembers when all this celebrity madness was a novelty. And he has seen other stars get devoured by getting too caught up in it.

“It’s part of the life we live,’’ O’Neal said. “We get a lot of good and we get a lot of bad with it. You have to accept it. Those that accept it can navigate society a little bit better. I’ve accepted since 17. You say, ‘Here, we’re going to put your name in the paper.’ It actually humbled me. Me? I’m in the paper? You want my autograph? I’m happy when people ask for my autograph. If it ever gets to the point where I don’t want to do it, I’ll just stay in the house.’’

This side of O’Neal was also on display at Mr. Bartley’s, where the line was too long to eat inside and linger over the burger they have named for him. So he settled into a bench to wait for a simple cheeseburger.

No celebrity rush to the front of the line for Boston’s biggest man on campus.

“Not going to use my superpowers today,’’ Shaquille O’Neal smiled.

Shira Springer can be reached at springer@globe.com.

© Copyright 2010 Globe Newspaper Company.