Friends and colleagues of Robin Williams were shattered by news of the Oscar-winning actor’s death, resulting in aching statements of grief about one of the funniest men who ever lived.

The 63-year-old actor was found dead in his Northern California home Monday afternoon, and investigators with the Marin County Sheriff’s Department stated the causes of death was “suicide due to asphyxia.” Williams’ family issued a statement saying that the actor had been battling depression.

Filmmakers who were close to Williams expressed disbelief at the loss.

Steven Spielberg, who worked with him on 1991’s Hook and was a longtime friend, acknowledged the passion for a connection that fueled the comic star: “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.”

Those close to Spielberg confirmed that during the filming of 1993’s Schindler’s List, Williams often spoke with Spielberg, cracking jokes to lift the director’s spirits during his darkest days on the Holocaust drama.

Garry Marshall, the producer who cast the young stand-up comic known for his wild onstage antics as a man from another world in the 1978-82 TV show Mork & Mindy, said simply: “He could make everybody happy but himself.”

“Robin was hands-down a comedy genius and one of the most talented performers I have ever worked with in television or film,” Marshall said in a statement. “To lose him so young at the age of 63 is just a tragedy. I will forever be in awe of his timing, his talent and his pure and golden creativity. … He was my friend and it is rare that you ever have a friend that is also a genius.”

Chris Columbus, who directed Williams in Mrs. Doubtfire (1994) and Bicentennial Man (1999), called the actor “one of our most inspired and gifted comic minds, as well as one of this generation’s greatest actors.”

“To watch Robin work, was a magical and special privilege,” Columbus said in a statement. “His performances were unlike anything any of us had ever seen, they came from some spiritual and otherworldly place. He truly was one of the few people who deserved the title of ‘genius.'”

Columbus also spoke of his personal relationship with Williams: “We were friends for 21 years. Our children grew up together, he inspired us to spend our lives in San Francisco and I loved him like a brother. The world was a better place with Robin in it. And his beautiful legacy will live on forever.”

Shawn Levy, who directed Williams as Teddy Roosevelt in the two previous Night at the Museum movies and the upcoming third installment, said he was “shattered by the loss of my friend and collaborator.”

“Onscreen and off, this was a formidable, incredible guy — generous in the best way: with his heart and humor, devoted to making others happy,” Levy said. “Over his remarkable career, Robin moved us to tears; sometimes from laughter, sometimes from humanity, sometimes both in the same moment, a feat that few performers have equaled.”

Night at the Museum: Secret of the Tomb is finished filming and well into the post-production phase. It’s due in theaters this December, and will be one of just a handful of final projects for Williams. “I will miss Robin deeply but I will never stop treasuring the phenomenal, enduring work he gave to us all,” Levy added. “Robin Williams was that rarest of things: a true and forever one-of-a-kind.”