Not sure how I missed this. Is this common knowledge? A fascinating story. Happened back in 1999.
As far as I know, Eugene Merle Shoemaker, from Los Angeles, is the only human whose remains have left the planet.
Follow the headline link, scroll down to the section labeled “Death”.
UPDATE: A number of folks have pointed me to this page, which lists people whose remains have been “buried in space”. Shoemaker remains the only person whose remains were placed on another celestial body. But a pretty fascinating list.