Taking to her Instagram stories, Blake wrote a long post remembering her co-star.

Blake Lively is honoring the “fiercely loyal” Michelle Trachtenberg. Lively, who starred alongside Trachtenberg on “Gossip Girl,” shared an...

Gossip Girl alum Blake Lively has joined in the ongoing tributes for her co-star Michelle Trachtenberg, whose death was confirmed this morning. The...

Hollywood mourns the unexpected death of actress Michelle Trachtenberg at 39. Known for roles in 'Buffy the Vampire Slayer' and 'Gossip Girl,' her...

Sarah Michelle Gellar, Taylor Momsen and Blake Lively are among those paying tribute to Michelle Trachtenberg, who died Wednesday. Trachtenberg was...

Sarah Michelle Gellar has poured her heart out in a gut-wrenching tribute to her "Buffy the Vampire Slayer" costar Michelle Trachtenberg after MT's...

“She was fiercely loyal to her friends and brave for those she loved.”

Michelle Trachtenberg’s untimely death at 39 has sent shockwaves through her fans and colleagues -- and her former "Gossip Girl" costar Ed Westwick...

Trachtenberg played Georgina Sparks on the show.

Blake Lively, Sarah Michelle Gellar and other stars remembered Trachtenberg’s work ethic and friendship in social media posts.