Her family’s representatives confirmed her death in a statement.

“It is with great sadness to confirm that Michelle Trachtenberg has passed away. The family requests privacy for their loss,” it said.

Police in Manhattan said they responded to an emergency call on Wednesday morning, and found Trachtenberg “unconscious and unresponsive”. She was pronounced dead at the scene.

“Criminality is not suspected. The medical examiner will determine the cause of death. The investigation remains ongoing,” the NYPD said in a statement.

Trachtenberg got her start in acting at age nine on the Nickelodeon television series The Adventures of Pete & Pete.

In the early 2000s, she was nominated for several acting awards – including a Daytime Emmy Award – for her role in Buffy the Vampire Slayer.

She also starred in films including EuroTrip, Ice Princess, Killing Kennedy, and Sister Cities.

US comedian Rosie O’Donnell, who starred alongside Trachtenberg in her Harriet the Spy debut, said her death was “heart-breaking.”

“I loved her very much. She struggled the last few years. I wish I could have helped.”

Former castmates on her most popular shows have also paid tribute.

English actor Ed Westwick, who played the character Chuck Bass on Gossip Girl, posted on Instagram a picture of Trachtenberg as her character in the show, Georgina Sparks.

“So sad to hear of the passing of Michelle Trachtenberg. Sending prayers,” he wrote.

Former Buffy the Vampire Slayer castmate David Boreanaz wrote on Instagram: “So very sad. Horrible news”.

Trachtenberg first appeared in Gossip Girl in 2008. She returned to the role for two episodes of the second season of HBO Max’s reboot in 2023.

Her last major acting role was in 2021 as the host of a true-crime docuseries Meet, Marry, Murder, which appeared on digital streamer Tubi.

In 2021, Trachtenberg accused Buffy the Vampire Slayer creator Joss Whedon of inappropriate behaviour on set, after her co-star Charisma Carpenter said she had been left traumatised due to the treatment she received from Whedon.