Sarah Michelle Gellar remembers late Michelle Trachtenberg

Sarah Michelle Gellar just paid a sweet tribute to Michelle Trachtenberg.

The Golden Globe nominee celebrated the posthumous birthday of her co-star who played her sister in Buffy the Vampire Slayer.

On what would’ve been Michelle’s 40th birthday, Sarah recalled meeting her years before the popular show.

"When you turned 16, it was hard not to still see you as the little girl I met on All My Children," the Scooby Doo star wrote on her official Instagram.

"When you turned 21, I had to teach myself to not see you as the little sister anymore. I can't imagine what 40 would have been like. This I know... it would be filled with love. Happy birthday @michelletrachtenberg," she further wrote sentimentally.

Michelle Trachtenberg passed away at the age of 39 in February, when she was found unresponsive in her midtown Manhattan apartment due to complications from diabetes mellitus.

She has been a child actor, taking the screen since the age of three, with her most famous works being portraying Slayer’s younger sister, Dawn Summers in Buffy the Vampire Slayer Season 5 as well as the 1996 comedy, Harriet the Spy.

Michelle Trachtenberg starred in several other Nickelodeon productions too and in 1997 she won a Young Artist Award for her performance in CBS's sitcom Meego.