Michelle Trachtenberg was known for her roles in 'Gossip Girl' and 'Harriet the Spy.' Where to watch her most memorable TV shows and films.

Michelle Trachtenberg, the actress best known for her roles as Dawn Summers on Buffy the Vampire Slayer and Georgina Sparks on Gossip Girl, has died. She was 39.

Trachtenberg was found unresponsive in her New York City apartment early Wednesday morning, a spokesperson for the NYPD told Yahoo Entertainment. Authorities said her death is not believed to be suspicious, and the cause of death is pending an official autopsy report. Sources told ABC News the actress recently underwent a liver transplant and may have been experiencing complications.

A child star who seamlessly transitioned into more mature roles, Trachtenberg first gained recognition in the 1990s on Nickelodeon's The Adventures of Pete & Pete, before landing the lead role in Harriet the Spy (1996). She became a household name on Buffy the Vampire Slayer, where she played Dawn Summers, the younger sister of Buffy (Sarah Michelle Gellar).

Last month, Trachtenberg reflected on her time co-starring with Gellar, sharing a photo of them together on Instagram with the caption: “Slay all day! Always loved this twinning photo of us!”

In 2008, Trachtenberg took on the role of Georgina Sparks, a cunning socialite on Gossip Girl. The character quickly became one of the show’s most notorious scene-stealers, earning her a Teen Choice Award nomination for Choice TV Villain in 2012. As she told Seventeen in 2009, playing an “evil” person like Georgina is “a lot more fun than playing the good girl.”

A New York City native, Trachtenberg also starred in a variety of films, including the raunchy teen comedy EuroTrip (2004), the ice skating drama Ice Princess (2005) and 17 Again (2009), alongside Zac Efron.

Here’s a look at some of Trachtenberg’s most notable roles and where to watch them.

Gossip Girl (2008–2012, 2023)

Trachtenberg played a scheming troublemaker in Manhattan’s elite circles. She first appeared in Season 1 as Serena van der Woodsen’s unpredictable former friend and later became one of the show’s most notorious villains. Georgina’s dramatic twists kept fans hooked for multiple seasons. In 2023, Trachtenberg reprised the role in two episodes of Max’s Gossip Girl reboot.

Where to watch: Streaming on Max and Netflix. Available to buy on Amazon and other VOD platforms.

Stream on Max

Stream on Netflix

Harriet the Spy (1996)

In the movie based on the beloved children’s book by Louise Fitzhugh, Trachtenberg plays an 11-year-old aspiring journalist in New York City who secretly documents the world around her — until her private notebook falls into the wrong hands. The film was a defining moment that marked Trachtenberg as a rising star.

Where to watch: Streaming free on Pluto. Available to buy or rent on Amazon and other VOD platforms.

Stream on Pluto

Buy or rent on Amazon

EuroTrip (2004)

In the film that saw her transition from a child star to a more adult role, Trachtenberg played Jenny, a witty and adventurous traveler who embarks on a chaotic journey across Europe with her friends. The film became a cult favorite.

Where to watch: Streaming on Xfinity Stream. Available to buy or rent on Amazon and other VOD platforms.

Stream on Xfinity

Buy or rent on Amazon

Ice Princess (2005)

Trachtenberg starred as Casey Carlyle, a brilliant student who applies her scientific knowledge to mastering the sport of competitive figure skating. A heartwarming coming-of-age story, the film is a favorite among fans of inspirational sports dramas.

Where to watch: Streaming on Disney+ and Xfinity Stream. Available to buy or rent on Amazon and other VOD platforms.

Stream on Disney+

Buy or rent on Amazon

Buffy the Vampire Slayer (2000–2003)

Introduced in Season 5, Trachtenberg played Buffy’s younger sister Dawn, whose arrival was shrouded in mystery as she was revealed to be a mystical key transformed into human form. Trachtenberg’s character grew from a vulnerable newcomer into a vital member of the Scooby gang.

Where to watch: Streaming on Hulu (and on Disney+ for the bundle subscribers), and free on Tubi. Available to buy or rent on Amazon and other VOD platforms.

Stream on Hulu

Stream free on Tubi