Justice League fans of a certain age (namely mine) often believe that J’onn J’onzz, the Martian Manhunter, is the heart and soul of the Justice League. A hero who’s been involved in every incarnation of the League, J’onn is the wise father-figure, the mentor, the strategist, and the backbone that holds the Justice League together.
Sadly, it’s not quite true. While he was one of the original founders of the team, he was also the first to leave the team to do other things for a while. Whether it was due to redundant powers next to Superman or just the fact that he’s generally been one of the few major Leaguers to not hold down a solo series for very long, J’onn has been removed from the League more than once, and may be just shy of iconic for many fans were it not for his appearance as one of the founders on the Bruce Timm-produced Justice League animated series.