The famed Democratic Senator from Nevada died Tuesday in Henderson, NV ... according to Nevada Gov. Steve Sisolak and current Senate majority leader Chuck Schumer.

The cause of death is unclear ... but Harry was diagnosed with pancreatic cancer back in 2018 and received intensive treatments.

Harry was a big deal in Nevada and Washington D.C. ... rising the political ranks after being born to a poor family in a tiny mining town in rural Nevada. He grew up as a boxer before getting into politics.

Reid served 34 years in Congress, starting as a Representative in 1983 before being elected to the Senate in 1986 and later becoming the chamber's Democratic leader following the 2004 election.

Schumer, who succeeded Reid as the Senate Democratic leader, is remembering Harry as "one of the most amazing individuals" and "tough-as-nails strong."

Being from Nevada, the home of the infamous Area 51, Harry became increasingly interested in UFOs ... and in 2007 he secured funding for a Pentagon program that investigated reports of UFOs and other related phenomena.

The UFO program, formerly known as the Advanced Aerospace Threat Identification Program, no longer exists but the government is still studying UFOs ... and things wouldn't be where they were today without Harry.

Reid was 82.