While I have always been a supporter of Mr. Mxyzptlk, the imp from another dimension who has harassed the Man of Steel in countless adventures (even serious Superman soapers), Bat-Mite …. eh, not so much.
I first met Bat-Mite not in the comics but on one of the several Batman animated shows, the first to feature the voices of Adam West and Burt Ward, the Dynamic Duo of the 1966 Batman TV show. Batgirl, Bat-Mite and even the Bat-Computer were all fully developed personalities and crime-fighters on that toon.
But Bat-Mite … something just did not feel right. Still takes me a grain of salt to accept a Robin (much less five or is it more?) in the Dark Knight’s life. Solo Batman, mysterious and street level Batman is my Batman. THE Batman!
The imp, thought by many to be a dimenion-hopper, regularly appeared in Batman, Detective Comics and World's Finest Comics for five years. Bat-Mite and Mr. Mxyzptlk teamed up four times in the pages of World’s Finest to plague Superman and Batman as well. In 1964, however, when the Batman titles were revamped under new editor Julius Schwartz, Bat-Mite vanished along with the other extraneous members of the Batman Family such as Ace the Bat-Hound.
After this, only three more Bat-Mite stories were published in the pre-Crisis DC Universe: two Bat-Mite/Mr. Mxyzptlk team ups in World's Finest Comics #152 (August 1965) and #169 (September 1967) and "Bat-Mite's New York Adventure" from Detective Comics #482 (February-March 1979), in which the imp visits the DC Comics offices and insists that he be given his own feature in a Batman comic. This story featured protestors with picket signs shouting "We want Bat-Mite!" outside the Tishman Building where DC's editorial offices were located at the time, and was accompanied by an editorial comment that this story was published specifically to acknowledge the actual requests of fans for this character's revival.
Later Bat-Mite appeared in a one-page story in the 200th issue of The Brave and the Bold.
Bat-Mite’s origins have been up for discussion for decades. After the continuity-changing 1985 Crisis on Infinite Earths was published, Bat-Mite was mostly removed from the Batman comics canon. Bat-Mite made an appearance in the series Legends of the Dark Knight, although he may have been the hallucination of the drug-addled criminal, Bob Overdog. This comic states that Bat-Mite is one of the many admirers of superheroes from another dimension. This version of Bat-Mite later appeared in Mitefall, a one-shot book which was a parody of the “Knightfall” Batman storyline, with Overdog in the Jean-Paul Valley role. In #6 of the 1999 World's Finest mini-series, Mr. Mxyzptlk encountered Bat-Mite, shortly after being mistaken for him by Overdog. While in this story the post-Crisis Bat-Mite encountered Batman for the first time, Superman and Batman subsequently concluded that Mxyzptlk had created him, inspired by Overdog's ravings.
The first post-Crisis appearance of Bat-Mite was in Batman #672, written by Grant Morrison. Batman is confronted with Bat-Mite (or "Might") after being shot in the chest and suffering a heart attack. Might, who bears a green insectoid creature on his back, claims to have come from "Space B at the Fivefold Expansion of Zrfff" (at times Zrfff has been used as the name of Mr. Mxyzptlk's home dimension). Only Batman sees him. As Batman is having an increasingly difficult time keeping his grip on reality during this period, it is possible that Might is a mental delusion.
In Batman #678, Might reappears at the last page, commenting, "uh-oh" to Batman's increasing delusions. He then, throughout the whole Batman R.I.P. series, appears to counsel the Batman of Zur-En-Arrh, a delusional personality manufactured by Bruce himself, to keep Batman able to fight in case he was mind-wiped or driven to insanity. Batman #680 reveals that Might is indeed a product of Batman's imagination and represents the last vestiges of Batman's rational mind within the Batman of Zur-En-Arrh, although when asked by Batman whether he is an extra-dimensional being or a figment of his imagination Bat-Mite responds that the fifth dimension is imagination.
To my knowledge, this loathsome creation has not raised his ugly head in the New 52. That in itself makes the reboot worth it, IMHO.