The beloved actor passed away at his home in Malibu, California on 14 September (09).
The tragic news came as a surprise to his pals on the TV show because he never complained about his disease to any of them - and even planned to take part in a screen reunion scheduled for later this year (09).
Gary Owens, who hosted the comedy programme, tells the National Enquirer, "He didn't complain or tell any of us.
"He was a dear friend, a great and wonderful man. I knew him even before Laugh-In. He was busy and active to the end. He'd been doing Boston Legal and was still making commercials."
Owens last saw his friend in July (09) when they discussed a Laugh-In get together: "He looked fine. He never complained. He was joking all the time. We were all looking forward to the reunion show. And he and I were laughing about some of the jokes and skits we planned to do.
"He was so excited about being back together with the old gang. He kept his illness a secret from all of us. But that was Henry - a trouper to the end."