Robin Williams' last tweet was dedicated to his daughter Zelda's birthday.

Robin Williams' last tweet was an insight into the actor's life, as fans flocked to the actor's social media accounts in search of reasons for his untimely demise.

Williams has been battling depression for quite some time, which worsened after fellow actor Christopher Reeves' death. His thoughts on the loss and on death: "It happens all the time, I know, but I know their kids, they're amazing, and to see them go through so much loss in one year - that's tough."

The actor's Twitter and Instagram accounts received quite the traffic after yesterday's news, with special interest in his final posts. Robin Williams' last tweet was a birthday message to her daughter Zelda, now 25.

" #tbt and Happy Birthday to Ms. Zelda Rae Williams! Quarter of a century old today but always my baby girl. Happy Birthday @zeldawilliams Love you!"

The tweet was linked to an Instagram post of Williams in his younger years and a baby Zelda on his arms, the actor gazing pensively at the camera.

Zelda has responded to Robin Williams' last tweet, quoting Antoine de Saint-Exupery in "The Little Prince:" "You - you alone will have the stars as no one else has them ... In one of them I shall be laughing. And so it will be as if all the stars were laughing, when you look at the sky at night ... You - only you - will have stars that can laugh. - I love you. I miss you. I'll try to keep looking up. Z."

Williams' wife Susan Schneider was "utterly heartbroken" with the loss.

"This morning, I lost my husband and my best friend, while the world lost one of its most beloved artists and beautiful human beings." (smh.com.au)

Williams is reported to reprise his role as the disguised nanny in "Mrs. Doubtfire 2" before he passed away.