Michelle Trachtenberg, known for her roles in 'Buffy The Vampire Slayer' and 'Gossip Girl', has died at 39. She was found in her New York City apartment, with no cause of death disclosed. Trachtenberg had recently undergone liver transplant surgery. She began acting at a young age and was best known for her role as Dawn Summers in 'Buffy'. Tributes from co-stars highlight her sensitivity and loving energy.