CinemaBlend Copy to clipboard Zack Snyderâs Justice League has movie fans buzzing about a cameo that will âblow hardcore fansâ minds.â One of the popular theories floating around out there is that this could be the the Martian Manhunter. Who is he and whatâs he all about? Keep reading for a primer on this perennial DC Comics fan-favorite. Martian Manhunter's First Appearance Was In A Batman Comic For comic book fans, Detective Comics is synonymous with Batman, but this wasnât always the case. Originally starting out life as an anthology comic book meant to compete with pulp-comics of time,