Jimmy Kimmel's Uncle Frank Dead at 77

8/23/2011 10:00 AM PDT

Jimmy Kimmel's Uncle Frank -- Dead at 77

"Uncle Frank" Potenza -- the silver-haired ex-cop who charmed audiences on his nephew's show, "Jimmy Kimmel Live!", died early this morning ... reps from the show have confirmed.

Uncle Frank spent 20 years as a New York City police officer -- before eventually becoming a staple on Kimmel's late night show in 2003.

The show released an official statement on Frank's passing -- saying his "kindness and humor" will be missed.

The show has not revealed Frank's cause of death.

Uncle Frank was 77.

10:45 AM: Jimmy tweeted about the situation ... saying, "thank you for your kind words about a very kind man - my Uncle Frank - who passed away this morning."