Actress Michelle Trachtenberg, who rose to fame as a child star in the 1990s and 2000s, has died aged 39.

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.

The American actress was best known for playing Buffy the Vampire Slayer’s younger sister Dawn Summers, and later took on the role of manipulative socialite Georgina Sparks in Gossip Girl – which ran from 2007 to 2012 – as an adult.

Trachtenberg made her film debut in Harriet the Spy in 1996, and she appeared in several Nickelodeon productions.

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Michelle Trachtenberg rose to fame in the early 2000s

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.

Authorities said her death was not being treated as suspicious.

“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.”

In a social media tribute to Trachtenberg, another Buffy castmate James Marsters said the actress was “fiercely intelligent, howlingly funny, and a very talented person”.

“She died much too young, and leaves behind scores of people who knew and loved her,” Marsters said.

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.