Michelle Trachtenberg, popular known for her roles in Gossip Girl and Buffy the Vampire Slayer, has died at the age of 39.

The actress was found dead by her mother on Wednesday at her apartment in New York. Police said she was unconscious and unresponsive when they arrived and EMS workers confirmed her death.

Although the cause of death is yet to be known, reports say Michelle recently had liver transplant surgery. She had also battled alcohol addiction for years.

Michelle started acting at the age of three in commercials. She became popular for her role in Adventures of Pete and Pete, before landing a big role in Buffy the Vampire Slayer, which won her a Young Artist award.

She have starred in several movies like Harriet the Spy, Inspector Gadget, Cop Out, and 17 Again.

Michelle was born in New York City on October 11, 1985. She grew up in Brooklyn with her older sister and later moved to California for high school.