"Please join us in raising a glass to Robin — goodbye, dear friend," the post continues. "Thank you for all the laughter and the cookies. We will miss you so very much."
The cause of death is currently undisclosed.
Robin has appeared in a slew of big-budget films, including Ocean's Eleven and The Lost World: Jurassic Park. He had a recurring role on Babylon 5 and appeared on an episode of NCIS last year.
"It is with great pain & shock Kitty & I mourn the loss of our friend Robin Sachs," writes fellow Buffy the Vampire Slayer actor Armin Shimerman on Twitter. "All who knew him, knew how special Robin was."
Our thoughts are with Robin's family and loved ones during this painful time.