The artist passed away Monday, according to his family. He'd been diagnosed with liver and kidney cancer in 2016 -- something spotlighted in a Chicago interview that chronicled his health challenges, as well as his contribution to music.

Casper is most famous for his catchy dance song, which he first cooked up in the studio back in 1998, and which he tweaked and re-released in 2000. The "Cha Cha Slide" has gone on to become a go-to favorite and staple at weddings and parties all over the world.

The making of the track is well-chronicled ... DJ Casper said he first made it with the intention of it being used for his nephew's aerobics class, but upon seeing how well-received it was -- and how much play it got in local fitness clubs -- he thought it had potential as a single, and made a second version for wide release.

The track got some radio play in Chicago and then blew up in the years to come. The infectious line dance, similar to the 'Electric Slide', literally gives you step-by-step instructions throughout the dance ... which is partly what's made it such a party staple.

Millions have danced to it over the years -- in addition to your cousin's wedding, the song's also been featured in tons of movies and TV shows ... like "SNL."

"Cha Cha Slide" had done well on several worldwide music charts, and is certified platinum in the UK. It's easily DJ Casper's main claim to fame.

Casper was 58.

RIP ... and cha cha real smooth.