Bob Saget has died at the age of 65 ... TMZ has learned.

Multiple sources connected to the iconic comedian and actor -- most famous for his starring role as Danny Tanner in 'Full House' -- tell us he passed away Sunday at the Ritz-Carlton in Orlando.

The Sheriff's Department and the fire department responded to the hotel around 4 PM ET ... after hotel security had found Bob in his room. We're told he was pronounced dead on the scene, but the circumstances of his death are still unclear.

Bob's been touring the country lately, hitting a lot of destinations throughout the state of Florida, including in Orlando, which got started in September and was supposed to take him through May.

On Saturday night, he was in Jacksonville doing a show at the Ponte Vedra Concert Hall ... where he actually shouted out the crowd early Sunday morning.