Sam Smith, Mark Ronson and Cat Power Hit Holiday Parties in New York

Holiday parties are a fixture in New York City, and there were plenty to choose from this week. Highlights included David Barton and Susanne Bartsch hosting a toy drive at Gym U NYC in Chelsea, and Gabriela Hearst and Yola Mezcal holding an event at Café Carlyle.

Collecting Toys at Gym U

On Thursday night, around 9 p.m., revelers in silver sequins and knee-high boots walked into Gym U NYC, David Barton’s new gym in Chelsea, carrying toys like trucks, dinosaurs and board games, as the smell of exercise mats filled the air.

They had come for the holiday party and toy drive that Susanne Bartsch, a New York nightlife fixture, and Mr. Barton, a gym and fitness entrepreneur, have been hosting since the 1990s.

Just past the doors, Ms. Bartsch, dressed in a sparkling red jumpsuit and a wig with reindeer-like antlers made of hair, greeted guests. As in years past, she wanted to: “Give people a chance to feel the spirit,” she said. “I can’t believe it is already Christmas. I feel like I’m in a time warp.”

Mr. Barton, wearing a ripped Ramones T-shirt, said they also just wanted to collect a lot of toys, adding that the party is “always a reminder of what we’re supposed to think about this time of year.”

Throughout the gym, D.J.s blasted a pulsing beat to a crowd of several hundred guests, including the singer-songwriter Sam Smith, the actress and comedian Sandra Bernhard, a co-host of the event, and Christian Cowan, a designer known for feathered club-wear popular with celebrities like Lady Gaga, Cardi B and Lil Nas X.

Partygoers, some of whom had worked out in the space earlier that day, waited in line at a bar near a chest press machine for white wine and umami margaritas. Adding some extra holiday cheer, muscular men in Santa hats danced on the equipment.

Near a Christmas tree surrounded by toys, Mr. Cowan, a co-host of the event, said that during the holidays, when it comes to friends and family, he often tries to introduce humor with his presents.

“I love to give people hilarious taxidermy,” he said, “like a parrot dressed up as a pirate,” and recalled the time he gave someone a frog purse with a zipper.

He continued: “I think it is much more fun to invest in making everyone laugh at Christmas than to make them feel like they got the thing they really wanted.”

On Monday night at Café Carlyle, the storied Manhattan cabaret venue, Chan Marshall, the singer best known as Cat Power, slipped between the Steinway piano and a rack of guitars. She filched an oyster from Justin Theroux’s table, then was out the revolving door to Madison Avenue for a cigarette.

Ms. Marshall was on the Upper East Side to perform at a holiday party hosted by Gabriela Hearst, the former creative director of Chloé, and Yola Jimenez and Gina Correll Aglietti, founders of the spirit brand Yola Mezcal.

Minutes later, the producer Mark Ronson emerged from a black S.U.V. Ms. Marshall congratulated him on the two Golden Globe nominations he had earned earlier that day for songs from the “Barbie” soundtrack.

He said he had gotten the news while grocery shopping. “I didn’t want to be thinking about it, so I was like, let me just go and get some blueberries,” he said.

Inside the dim, mural-lined bar, more than a hundred attendees from the worlds of music, fashion and media did their best not to spill their mezcal martinis or dribble their crab tacos.

Guests included Katie Couric, who greeted Mr. Ronson warmly; Mel Ottenberg, the stylist and editor in chief of Interview Magazine; the actress Grace Gummer; and Tremaine Emory, the founder of Denim Tears and the former creative director of Supreme.

Once guests had settled, Ms. Hearst climbed onstage. “Thank God I’m dressed like a meringue,” she said, referencing a creamy one-shoulder dress of her own design.

Ms. Hearst announced that her namesake brand and Yola Mezcal would donate a portion of their sales from December to Save the Children, which provides humanitarian assistance to young people through its children’s emergency fund.

“The suffering out there is great,” Ms. Hearst said. “Just to celebrate how lucky we all are that we’re here, the most punk thing to do is to show joy, and to show awareness.”

On a tight stage, Cat Power performed “Georgia on My Mind” with Mr. Ronson beside her on guitar. The Swedish singer Lykke Li then asked the crowd to sing the chorus of her song “I Follow Rivers,” which Ms. Hearst filmed on her iPhone.

Mr. Ronson and the singer Andrew Wyatt took the microphone for a two-man arrangement of “I’m Just Ken,” a song from “Barbie.”

“I’m just Ken and I’m enough,” Mr. Wyatt declared, in the room once graced by the cabaret legends Bobby Short and Elaine Stritch. “And I’m great at doing stuff.”