Since news of Robin's death broke, fans have taken to the comments section of the photo to share their condolences with his family.
"Crushed...you are irreplaceable," wrote one. "I grew up watching your movies, it's like a piece of my childhood is gone," posted another. Hollywood stars have also been speaking out about his passing -- see their messages of remembrance here.
The actor was found dead in his home at the age of 63 on Monday, August 11 after a suspected suicide.
UPDATE: On Monday night, Zelda tweeted out a quote from French writer Antoine de Saint-Exupéry and the message "I love you. I miss you. I'll try to keep looking up."