President 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 an alien . . . but he ended up touching every element of the human spirit."
Steve Martin: "I could not be more stunned by the loss of Robin Williams, mensch, great talent, acting partner, genuine soul."
Robin's "Mrs. Doubtfire" daughter 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."
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."
Jason Alexander: "Ah Robin, I'm so sorry the earth couldn't stay worthy of you. Hope happiness awaits you."
Anna Kendrick: "O Captain! My Captain! Rise up and hear the bells. Rise up, for you the flag is flung, for you the bugle trills." (That's a "Dead Poets Society" reference.)
Lindsay Lohan: "Mr. Williams visited me the first day of filming The Parent Trap. I will never forget his kindness. What an enormous loss. My condolences."
Goldie Hawn: "Oh Robin . . . Our hearts are broken. Rest in peace darling. We loved you."
Ellen DeGeneres: "I can't believe the news about Robin Williams. He gave so much to so many people. I'm heartbroken."
Steve Carell: "Robin Williams made the world a little bit better. RIP."
John Mayer: "The first thing I ever wanted to be when I grew up was Robin Williams' inhabiting of Popeye."
Mindy Kaling: "I am named after a character from a Robin Williams TV show when my parents still lived in Africa. He meant so much, to so many, so far away." "Mork & Mindy", obviously.
Mindy herself, Pam Dawber, said, quote, "I am completely and totally devastated. What more can be said?"
"Night at the Museum" co-star Ben Stiller: "A tweet cannot begin to describe the hugeness of Robin Williams heart and soul and talent. This is so sad."
Sarah Michelle Gellar just posted a montage of pictures of the two of them. Probably from the set of their now-canceled sitcom"The Crazy Ones".