Throughout his 46 years playing Big Bird on “Sesame Street,” Caroll Spinney has always stood apart from the show’s other puppeteers.

For one thing, the full-body costume means he can’t easily interact with cast members. For another, it means he can cry without anyone noticing.

He’s done it a few times, most notably while singing “Bein’ Green” at mentor Jim Henson’s funeral; another was during the darkest period of his life, when divorce and depression made him thankful the suit hid his tears.

Those tears — as well as plenty of smiles — are explored in the new documentary “I Am Big Bird,” opening Wednesday at the IFC Center. Fans will see how Spinney, now 81, evolved from being a kid bullied for playing with dolls to developing Big Bird and Oscar the Grouch when “Sesame Street” debuted in 1969. It’s a bittersweet ode that’s also the love story of Spinney and his second wife Debra, who met on the show.

“Why we care so much about Big Bird, and Oscar, too, is we know inside those creatures beats the heart of a great human being,” “Sesame Street” creator Joan Ganz Cooney says in the film. You might have guessed that part already, but here are five things you don’t know about the man who is Big Bird.

He’s related to Barack Obama

Spinney and the president of the United States share a distant great-grandfather, Josiah Cook, making them ninth cousins, twice removed. The puppeteer got the news via a cousin who had a genealogist trace the family’s history.

“He gave me a whole family tree that proves it,” Spinney tells The Post. When Michelle Obama came to “Sesame Street” for an appearance, she said to Spinney: ‘Well, cousin, at last we meet.’”

The days weren’t always so sunny

It’s hard to picture, knowing Big Bird to be the embodiment of optimism, but Spinney once considered suicide. In 1971, the puppeteer discovered that his then wife and mother to his 1-year-old son was cheating on him. They got divorced, setting off a spiral of depression.

“I’d put food in my mouth and I’d say, ‘Chew it, for God’s sake! Swallow it! You’re not eating,’ ” he says.

One day on set, a crew member complimented his Big Bird acting. She couldn’t see the tears streaming down his face inside the suit.

At home, he opened the window of his apartment, looked down the nine stories and said to himself, “I could just jump out and be over with it.”

Luckily, he closed the window, called a friend and went to the movies, and never thought about suicide again. A year and a half later, he met Debra, and they’ve been in love ever since.

“No matter how black a day, if you can just hold on, the sun will eventually come out for you,” he says in the film.

He’s not the only Big Bird

Spinney is inextricably tied to Big Bird’s identity — but he’s not the only one who gets to wear the yellow suit. His apprentice, 44-year-old Matt Vogel, has been waiting in the wings 17 years for Spinney to retire. In the meantime, Vogel acts as a producer and puppeteer on the show, occasionally donning the costume.

“Most people retired years ago, but I don’t want to retire,” Spinney says. “I don’t see a point to it.”

He was almost on the doomed Challenger space shuttle

Big Bird — with Spinney in the suit — was originally slated to be a part of the Challenger space-shuttle mission in 1986, in the hopes of renewing kids’ interest in America’s space program. But the suit wouldn’t fit on the shuttle, so NASA scrapped the plan. The shuttle exploded soon after takeoff, killing its seven crew members — including schoolteacher Christa McAuliffe, who was selected in Spinney’s place.

He was once making so little money that he almost quit

Playing a giant bird didn’t automatically lead to a giant nest egg. In the early days of “Sesame Street,” the show was a hit, but Spinney’s $375-a-week paycheck left him unable to afford rent for his Upper West Side apartment. The apartment was hardly worth the rent: It was above a noisy bus stop and his neighbor swung a pet beagle by the ears until the dog screamed.

Spinney left the apartment and slept on friends’ couches; meanwhile, he was making more money doing puppet work in Boston, even as Big Bird landed on the cover of Time magazine. Legendary puppeteer Kermit Love, who helped create the Big Bird costume, talked him into staying.

“‘You’ll never find an opportunity like this again,’” Spinney recalls him saying. “It was exactly what I had gone looking for.”