Michelle Trachtenberg, the actress who rose to fame as a precocious child star in “Harriet the Spy” and went on to have memorable roles on TV shows including “Gossip Girl,” has died, according to the New York City police.

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.