Paul Reubens did more than tickle people's funny bones. He also touched their hearts.

Reubens, an actor and comedian best known for his comedic man-child character Pee-wee Herman, died Sunday of cancer, his estate confirmed on his official Instagram page Monday. "Last night we said farewell to Paul Reubens, an iconic American actor, comedian, writer and producer whose beloved character Pee-wee Herman delighted generations of children and adults with his positivity, whimsy and belief in the importance of kindness," the announcement read.

The post included a quote from Reubens himself, apologizing to fans for dealing with his health privately. "Please accept my apology for not going public with what I’ve been facing the last six years," he said. "I have always felt a huge amount of love and respect from my friends, fans and supporters. I have loved you all so much and enjoyed making art for you."

An outpouring of tributes came in online from Reubens' friends in the entertainment world mourning the actor's death.

"A completely original actor and friend; I mourn his loss," Bette Midler wrote on Twitter. "This is so hard to believe."

"Paul Reubens was like no one else − a brilliant and original comedian who made kids and their parents laugh at the same time," Jimmy Kimmel tweeted. "He never forgot a birthday and shared his genuine delight for silliness with everyone he met. My family and I will miss him."

Mark Hamill quoted an excerpt from Reubens' apology, directly responding to the actor's note about loving his fans and enjoying "making art for you."

"We loved you right back, Paul... (and) can't thank you enough for the lifetime of laughter," Hamill wrote.

"No tweet can capture the magic, generosity, artistry, and devout silliness of Paul Reubens," Conan O'Brien tweeted. "Everyone I know received countless nonsensical memes from Paul on their birthday, and I mean EVERYONE. His surreal comedy and unrelenting kindness were a gift to us all. Damn, this hurts."

"Goodbye Paul. Goodnight sweet prince," Cher tweeted. "May flights of angels sing thee to thy rest."

David Hasselhoff shared a black-and-white throwback photo of himself with Reuben in his tribute.

"Paul Reubens was a great friend," Hasselhoff wrote on Twitter. "He gave me the Muppets for my birthday and never forgot anyone’s birthday from our class. He was in my class at (the California Institute of the Arts) and we had the same business manager. He was always kind to me and to everyone. He will be missed."

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Contributing: Kelly Lawler, USA TODAY