So, after Water Boy was killed off in issue #5 of his own comic, Starman came along to take up the numbering of the comic from #6 on.
The reason for the connection between the two is tenuous and strange: after Water Boy's death, Mary Marvel and Zippy Zap are attending a public display of the results of the investigation into both his and his arch-rival The Spearsman's deaths. Kinda like a superhero Warren Commission Report.
A test tube of "gamma cosmic waste" extracted from The Spearsman's blood is on display. The test tube, of course, explodes and turns the Conrad Janis-looking lecturer into a powerful guy whose head is shaped like a big star. Uh-huh.
Greg Hisle draws Mary Marvel in the panels in which she appears.