In a statement to PEOPLE on Thursday, Rickles’ longtime rep Paul Shefrin said: “Emmy-Award winning iconic comedian Don Rickles passed away at his home Los Angeles this morning (Thursday) as a result of kidney failure.”
Prior to his death, the veteran comedian and actor sat down with the former Late Night and Late Show host a handful of times.
After learning of Rickles’ death, Letterman, 69, said in a statement obtained by PEOPLE: “Don coming on our show was always a highlight for me. Just endless mischief and nonsense, and a guy who would make the audience go completely crazy.”
“Such a professional, such a gentleman,” continued Letterman, who retired from his late-night hosting duties in May 2015. “I already miss him.”
FROM COINAGE: The Most Expensive TV Shows of All Time
Rickles, who would have turned 91 on May 8, is survived by his wife of 52 years, Barbara, as well as their daughter Mindy Mann and her husband Ed, and Rickles’ two grandchildren: Ethan and Harrison Mann.
According to Shefrin, funeral services will be private. In lieu of flowers, it is suggested that donations be made to the Larry Rickles Endowment Fund at Children’s Hospital Los Angeles.