** Benn Blanx. See YMMV/JusticeLeagueOfAmerica.
** J'onn's own [[CainAndAbel twin brother]], Ma'alefa'ak J'onzz--or [[NamesToRunAwayFrom Malefic]]--had his natural psychic powers stripped by his own people by abusing his telepathic powers, using them to cruelly MindRape J'onzz's wife. [[DisproportionateRetribution Out of petty spite]], Malefic engineered a [[GenocideFromTheInside fatal psychic plague among his people]], causing whatever Martian that used their psychic powers to horribly burn and die as a result and singlehandedly destroying almost his entire race as a result. Pursuing his brother J'onn to Earth in a single-minded crusade to end his brother's life and complete his genocide, Malefic tried various times to destroy his brother and all those close to him, murdering the partner of his human identity, Karen Smith, and trying to mentally drive his own brother to suicide through a remnant of himself before his final death.
* FashionVictimVillain: Both Mr. V (who wore a business suit jacket, a T-shirt, and slacks) and Commander Blanx (in his green and sickly orange get up).
* SugarWiki/FunnyMoments: To meet with Bruce Wayne and Clark Kent in Japan, J'onn utilizes one of his aliases, a female Japanese reporter named [[Franchise/SailorMoon Rei Hino]]. Batman recognizes him anyway, noting in part that [[http://sailormoonnews.com/2012/12/28/did-batman-read-sailor-moon/batman_calls_out_martian_manhunter_hino_rei_full_page/ the name is a dead giveaway]].
* NewerThanTheyThink: Not many people know this, but Mars was fully populated in the Silver Age. The concept of J'onn being the last Martian didn't come until later.
* SoBadItsGood: Back in 1959, there was a story in which J'onn J'onzz goes up against a foe called ''the Human Flame''... who was a schlub named Mike who built a "crime suit" that shot electric bolts and fire out of little spouts on the chest. That's right: ''Flaming Shock-Nipples of Crime!'' He dropped off the face of the earth for 50 years and was eventually brought back as an IneffectualSympatheticVillain in ''[[CrisisCrossover Final Crisis]]''.
* UncannyValley: J'onn's almost-but-not-quite human shape sometimes disconcerts people. (And this was the form he created to avoid scaring people!)