A Shinigami (死神) appears as the antagonist of the Shonen Sunday story Shinigami.
Shinigami had appeared in Shigeru Mizuki's works before, most notably in Kappa no Sanpei, before one debuted in GeGeGe no Kitarō.
Shonen Sunday/Second Anime
In the story, he has the Witch pose as Kitarō's mother Iwako in order to attempt to steal his soul.
His story was adapted for the 1971 anime, although the character was combined with Shinigami No. 106 from Salaryman Shinigami to create the character Shinigami No. 42.