But his daughter Zelda Williams says there's no point in trying to determine what drove the actor to suicide at age 63.
"It's not important to ask," Williams, 25, said through tears while speaking out for the first time since her father's death to NBC News correspondent Kate Snow.
"A lot of people who have been through it and lost someone, the ones that I've found who have gone on to lead very full lives, found that they just had to know that there's no point questioning it," she said in the segment, which aired on the Today show Thursday, "and there's no point blaming everyone else for it, and there's no point blaming yourself or the world or whatever the case may be, because it happened, so you have to continue to move and you have to continue to live and manage."
Instead, the young actress is focused on carrying out the charitable causes near and dear to her dad's heart. On Friday, she'll present a Noble Award for the Challenged Athletes Foundation and establish the Robin Williams Fund.
As for his comedic legacy, Williams said she has been touched by the outpouring of support from the public.
"They knew a dad that he was proud of them knowing because he was an incredibly kind and incredibly caring man, and he was also private and very calm and very subdued," she said. "The side of him that people know and love and that is attached to their childhood is the characters that he had so much fun being, and that's what's important, and I think that's what a lot of people will hold on to."
Williams also explained the meaning behind her new tattoo ("Hummingbirds are fun and flighty and strange – it's hard to keep them in one place, and Dad was a bit like that") and how she hopes to eliminate the stigma surrounding mental health.
"People are finally starting to approach talking about illnesses that people can't really see," she said. "Nothing happens immediately, but I think we're on our way."
Frank Edwards / Getty