At 11 p.m., outside the Mark Hotel on the Upper East Side of Manhattan, gawkers pressed up against police barricades, hoping to catch a glimpse of someone — anyone — who had been at the Met Gala and was now showing up to the first of its after-parties.

Jeremiah Scott, who said he was an aspiring designer, put on his boxy double-breasted blazer, pulled up his studded cargo pants and headed for the front of the line. Within seconds, he and a friend — a rapper who goes by the tag NYXJVH and who wore a studded $3,000 Margiela mask that covered his entire face — strolled through the lobby toward an event space where waiters passed out crispy spring rolls and a D.J. played vintage Madonna. Neither Mr. Scott nor his friend was on the list, but they managed to blend in with the invited guests.

In the center of the room was a giant gold statue in the shape of Karl Lagerfeld’s face. Posing against it was Amanda Lepore, the nightlife diva whose physical transformation into an hourglass-shaped kewpie doll put her in the plastic surgery pantheon alongside Jocelyn Wildenstein.

A reporter asked Ms. Lepore if she had attended the ball, which celebrated the opening of a Karl Lagerfeld retrospective at the Met’s Costume Institute. “No,” she said, disappearing into the crowd.

Neither had Aquaria, the Season 10 winner of “RuPaul’s Drag Race.”

Like a number of the gala’s actual attendees, Aquaria had on a catsuit that paid homage to Choupette, Mr. Lagerfeld’s tortie Birman cat. “I’m here representing the mentally unwell members of the L.G.B.T.Q. community,” she said, adding that fashion doesn’t have to be so serious.

After a cockroach became a viral sensation by crawling across the carpeted steps at the Met, who could argue with that?

Certainly not the gala’s main organizer, Anna Wintour, who has shown a willingness to move with the moment, even if that means putting on a yearly bacchanal that increasingly feels more like the world’s highest-wattage Halloween parade than fashion’s biggest night out.

And certainly not Mr. Lagerfeld, a man who, until a few months before his death at 85, hit the social circuit in Hedi Slimane suits, spouting proclamations about the pointlessness of preciousness.

“There is nothing worse than bringing up the ‘good old days,’” he once said. “To me, that’s the ultimate acknowledgment of failure.”

Into the Mark waltzed Lisa Airan, a cosmetic dermatologist whose skills with syringes have prevented many a gala regular from becoming an example of what once was.

Ms. Airan wore a cream-colored Grecian dress. Holding the train was her husband, the cosmetic surgeon Trevor Born.

“It was designed with A.I.,” Ms. Airan said, naming Discord as the software program that had dreamed it up. “Then I got Gilles Mendel to execute it. I thought that if Karl was alive today, that’s what he would do. Because he was so forward thinking.”

To Ms. Airan, who said she attends the gala every year, there had been nothing about the crowd at this year’s event that indicated a drop in quality. “Everyone looked great,” she said. “This was the first year it was sponsored by Ozempic.”

Only the second part of that statement was a joke, she was quick to add.

Around midnight, a few genuinely famous people had arrived at the Mark.

James Corden stood by the bar in his black tuxedo pants and blue tuxedo jacket. Brian Tyree Henry, a star of the beloved FX series “Atlanta,” posed for photographers a few feet away.

It was Mr. Henry’s first time as a Met Gala guest. Although he said he had never met Mr. Lagerfeld, he had been placed by Vogue at the Chanel table, a clear measure of his status near the top of this year’s heap.

“It was unbelievable,” Mr. Henry said of the gala. “Everyone looked stunning. Nothing like a black and white ball.”

Many of the guests started heading downtown, to the Standard Hotel, the site of another after-party.

In the “Mad Men”-meets-Rainbow Room top-floor space, professional dancers gyrated on platforms in white spray-painted bodysuits that brought to mind Keith Haring’s collaboration with Grace Jones. The designer Jeremy Scott stood at the bar. The model Coco Rocha passed by in a sparkly gold dress. The host was Janelle Monáe, who earlier in the evening had served as a Met Gala co-chair.

Ms. Monáe had arrived at the Metropolitan Museum of Art in a Chanel-inspired Thom Browne black and white coat, which she stripped off in front of photographers to reveal a see-through hoop skirt, under which she wore a black bikini with Lagerfeld-like pearls dangling from the waistline. Now she had ditched the skirt and went around with a black cape draped across her shoulders.

The star wattage in the Standard crowd did not approach that of earlier years, when Beyoncé, Jay-Z, Uma Thurman, Donatella Versace and Madonna parked themselves at banquettes and partied until the wee hours, but there were still some big names in the room.

Mary J. Blige arrived as Ms. Monáe and the dancers climbed aboard the bar to put on a short show. After that, Lil Nas X and Billie Eilish strolled in.

Downstairs, an Escalade big enough to have Lizzo’s name skywritten in the ozone layer pulled up, and out she stepped. “We love the blond hair,” a fan yelled from the middle of the Belgian-block street.

Pier Paolo Piccioli, the designer at Valentino, headed off in a car, bound for Virgo, a basement nightclub on the Lower East Side, where a party hosted by Dua Lipa was taking place.

To get there, one descended a dark staircase lit from both sides in neon red.

Florence Pugh, her head newly shaved, stood at the bar in the front room. Ms. Lipa was at the front of a narrow, packed dance floor, dancing in an outfit adorned with pearls. Dom Pérignon was in abundance.

Penélope Cruz took a quick tour of the room in her black Chanel dress shortly before the arrival of the director Baz Luhrmann and the designer Prabal Gurung. Mr. Gurung mentioned that this was the third after-party he had attended, adding that it was, in his own estimation, “too many.”

But with the music still blasting, people still dancing, and Rihanna and ASAP Rocky moments away in an ozone-shattering vehicle of their own, it would be hours before things ended there or at the Box, a nearby burlesque club where Sean Combs, the rapper known as Diddy, held a party of his own.

There, Usher sipped a drink in front of the D.J. booth. The singer Juan Luis Londoño Arias, who performs as Maluma, was on the balcony, flashing peace signs to the crowd below. Paris Hilton swayed from side to side, eyes hidden behind white sunglasses, with Marc Jacobs at her side. Naomi Campbell danced nearby. Mary J. Blige stood next to Mr. Combs as he played emcee.

“If you’re tired, you can leave,” he said into the mic.