Dawn Summers on 'Buffy the Vampire Slayer' was magical energy turned human. Michelle Trachtenberg made her everyone's kid sister.

Michelle Trachtenberg, the actress who rose to fame as a child star with films like “Harriet the Spy” and went on to have memorable roles on TV shows including “Gossip Girl,” has died, according to an NYPD source.

Buffy the Vampire Slayer fans are mourning the heartbreaking death of Michelle Trachtenberg with a walk down memory lane. After the actress passed away at the age of 39 on Feb. 26, Buffy lovers are looking back on her iconic performance as Dawn Summers and planning rewatches of the series in her honor.