Georgina Sparks was not Gossip Girl, but she might as well have been.

The character, a socialite who trafficked in wild manipulation, convoluted scheming and plenty of narcotics, was a main antagonist of the 2000s teen drama series that aired on the CW network, an inveterate plotter in a statement necklace. (“Gossip Girl” is available to stream on Max, Netflix and Tubi.) A former queen bee turned problem child who refused to be banished to boarding school in Switzerland, she had the Upper East Side wrapped around her manicured finger.

Georgina was played by the actress Michelle Trachtenberg, who was found dead at 39 in her Manhattan apartment on Wednesday. Her performance as the teenage supervillain brought an arch flair to a character who was only a minor figure in the novels that were the basis for the show, but became a fan favorite onscreen.

As an actress, Trachtenberg was not a queen of mean — or at least not only that. She started performing as a child, and audiences watched her grow into the different modes of young womanhood throughout the ’90s and 2000s.

In her title role in the 1996 children’s movie “Harriet the Spy,” she was clever, opinionated and driven in a way girls didn’t often get to be onscreen. In “Buffy the Vampire Slayer,” the influential horror-dramedy, she was introduced mid-series as Buffy’s bubbly yet stubborn younger sister, Dawn, balancing supernatural forces with heartfelt teenage emotion.

In the 2005 sports comedy-drama “Ice Princess,” she played a geeky teenager who dreamed of becoming a professional figure skater. I remember watching “Ice Princess” on the Disney Channel as a child, drawn in by Trachtenberg’s likability: She was beautiful, brainy and talented, unapologetic about her skills but never arrogant.