"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."
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