On Monday, the news of Robin Williams' apparent suicide sent shock waves through the Hollywood community and the world. The beloved 63-year-old actor's death has struck a cord with family, friends and fans alike. Celebrities and others have flocked to social media and other outlets to express their deep dismay over the Oscar winner's tragic death.

Williams' wife Susan Schneider released a statement via the New York Times and his daughter Zelda posted a touching quote on her Twitter account. They are certainly not alone in their despair.

Here are just some of the celebrities who posted about their heartbreak:

Sarah Michelle Gellar:
    "This is without question, the hardest few words I have ever tried to write. My life is a better place because I knew Robin Williams. To my children he was 'Uncle Robin', to everyone he worked with, he was the best boss anyone had ever known, and to me he was not just an inspiration but he was the Father I had always dreamed of having. There are not enough adjectives to describe the light he was, to anyone that ever had the pleasure to meet him. I will miss him everyday, but I know the memory of him will live on. And to his family, I thank them for letting us know him and seeing the joy they brought him. Us Crazy Ones love you. God, grant me the serenity to accept the things I cannot change, The courage to change the things I can, And the wisdom to know the difference."

Mork and Mindy star Pam Dawber : "I am completely and totally devastated. What more can be said?"

President Barack Obama: "Robin Williams was an airman, a doctor, a genie, a nanny, a president, a professor, a bangarang Peter Pan, and everything in between. But he was one of a kind. He arrived in our lives as an alien -- but he ended up touching every element of the human spirit. He made us laugh. He made us cry. He gave his immeasurable talent freely and generously to those who needed it most -- from our troops stationed abroad to the marginalized on our own streets. The Obama family offers our condolences to Robin's family, his friends, and everyone who found their voice and their verse thanks to Robin Williams."

Sally Field: "I feel stunned and so sad about Robin. I'm sad for the world of comedy. And so very sad for his family. And I'm sad for Robin. He always lit up when he was able to make people laugh, and he made them laugh his whole life long.... tirelessly. He was one of a kind. There will not be another. Please God, let him now rest in peace."

Steven Spielberg: "Robin was a lightning storm of comic genius and our laughter was the thunder that sustained him. He was a pal and I can't believe he's gone."

Mara Wilson: "Very sad, very upset, very glad I did not have to hear about this though Twitter. Probably going to be taking some time off it for a while."

Kathy Bates: "Magnificent Robin RIP. The Black Dog won the war. So sad. Thank you for the quarter you loaned me to call my mom at the '90 Globes."

Rain Pryor : "RIP Robin Williams hope daddy and Carlin were there to greet you. My heart is broken."

Steve Martin: "I could not be more stunned by the loss of Robin Williams, mensch, great talent, acting partner, genuine soul."

Kevin Spacey: "Robin Williams made the world laugh & think. I will remember & honor that. A great man, artist and friend. I will miss him beyond measure."

Danny DeVito: "Heartbroken"

John Travolta: "I've never known a sweeter, brighter, more considerate person than Robin. Robin's commitment as an artist to lifting our mood and making us happy is compared to none. He loved us all and we loved him back."

Chevy Chase: "Robin and I were great friends, suffering from the same little-known disease: depression. I never could have expected this ending to his life, and to ours with him. God bless him and God bless us all for his LIFE! I cannot believe this. I am overwhelmed with grief. What a wonderful man/boy and what a tremendous talent in the most important art of any time - comedy! I loved him."

Bill Cosby‏: "I'm stunned!"

Judd Apatow: "When I was 18 I got a job as an intern at Comic Relief just to be near him. A genius and a truly kind man who made the world a better place."

Ben Stiller: "A tweet cannot begin to describe the hugeness of Robin Williams heart and soul and talent. This is so sad. #RobinWilliams. I met him when I was 13 and a huge fan and he was so kind and I watched him be kind to every fan i ever saw him with...And with other actors he was so generous and brilliant. He made everyone feel special and equal around him even though he was the genius...His heart was so big and even if you didn’t know him, what he gave everyone was that same spirit in his work, so we all felt it…His impact on the world was so positive. He did so much good for people. He made me and so many people laugh so hard for a very long time. And because they don’t really tweet, this message represents all the Stillers (Jerry, Anne and Amy) who Robin was a great friend to. Xxxxx"

Goldie Hawn: "Oh Robin...Our hearts are broken. Rest in peace darling. We loved you."