According to his team, Macdonald passed away Tuesday after a multi-year, private battle with cancer that he kept hidden from the public, fighting the disease behind the scenes for nine years.

His longtime producing partner, Lori Jo Hoekstra, says ... "He was most proud of his comedy. He never wanted the diagnosis to affect the way the audience or any of his loved ones saw him. Norm was a pure comic. He once wrote that ‘a joke should catch someone by surprise, it should never pander.’ He certainly never pandered. Norm will be missed terribly."

The revelation is absolutely stunning ... as Macdonald was a household name in comedy, and has been for decades. He's perhaps most famous for being one of the OG 'Weekend Update' co-hosts on 'Saturday Night Live' -- among many other TV shows and movies over the years.

He starred on 'SNL' from '93 to '98 ... what many consider the glory years of the sketch comedy series. Like many other comedians, 'Saturday' gave Norm his jumpstart -- and his career only skyrocketed from there.

Norm went on to star in (and make a number of memorable cameos) in famous flicks like 'Billy Madison,' 'Dirty Work,' 'Dr. Doolittle,' 'Screwed,' 'Deuce Bigalow,' 'Man on the Moon' ... and several other Sandler flicks. He also had his own sitcom, "Norm" ... plus his own talk show at varying points. Speaking of late-night, Norm was a regular guest for David Letterman, Conan O'Brien, Jimmy Fallon, Larry King, Jay Leno, Howard Stern ... and many other iconic hosts.

His TV resume is just as impressive -- he starred in (and wrote for) 'Roseanne,' 'My Name is Earl,' 'The Drew Carey Show,' 'Family Guy,' 'The Fairly Odd Parents,' 'The Orville,' 'The Middle,' 'Sunnyside,' 'A Minute with Stan Hooper,' and many, many others.

Norm was infamous for his edgy humor -- which, of late, was clashing with modern-day sentiments ... including PC/cancel culture. In fact, the last time we saw him -- just a few years ago -- he was telling us that he couldn't really be funny anymore because of political correctness.

Keep in mind, Norm famously claimed NBC exec Don Ohlmeyer got him yanked him off 'Weekend Update' in 1997 because he kept slamming Ohlmeyer's pal O.J. Simpson with jokes about the double murders.

The guy was still hitting stages even in the past year ... he was doing standup at the Improv, talking coronavirus -- and despite him battling cancer right then and there, he still looked sharp ... maintaining the same witty humor he'd always had.

Norm is survived by his son, Dylan. He was just 61.