Blake Lively and Alyson Hannigan are among the former "Gossip Girl" and "Buffy" actors mourning the death of their one-time co-star, Michelle Trachtenberg.

The veteran actress, born in New York and raised in Brooklyn before moving to L.A., moved seamlessly from the big and small screens throughout her decades long career.

Actress Michelle Trachtenberg, who rose to fame as a child star in the 1990s and 2000s, has died aged 39. Police in Manhattan said they responded to an emergency call on Wednesday morning and found Trachtenberg "unconscious and unresponsive". She was pronounced dead at the scene.