Even non-comic fans knows that Gotham City is protected by the legendary Batman, but what about the other winged creature soaring over Gotham at night - Man-Bat? While many consider him a monster, the Batman villain began as a man with truly good intentions. Similar to Marvel's Spider-Man villain the Lizard, Man-Bat's alter-ego, Dr. Robert Kirkland "Kirk" Langstorm, is a scientist who's attempt to better humanity would not only doom him, but also his family to a life of horror and tragedy.
Created by Frank Robbins, Julius Schwartz, and Neal Adams, Langstorm first appeared in Detective Comics #400 (1970) as a zoologist working to give humans sonar sense. The experiment worked, but Dr. Langstorm's new abilities came with the side effect of transforming him into a human/bat hybrid. Although the doctor originally maintained his intelligence and even assisted Batman in a battle against costumed thieves, he would became Batman's enemy when the two fought over Langstorm attempting to steal the chemicals necessary to reverse his condition. After being confronted by the Caped Crusader, Kirk's transformation was complete and the almost-feral Man-Bat fought Batman in the Batcave, which Langstorm had accidentally discovered by following a wayward bat home.
Man-Bat eventually reunited with his estranged fiancee Francine and was able to convince her to take the same extract he had. Believing that the man she loved was still within Man-Bat, Francine drank the formula and transformed into a similar bat-like creature, later dubbed She-Bat. The mutated Kirk and Francine's wedding was interrupted by an objecting Batman who administered the cure and transformed them back to normal, at least for the time being. But over the years, the couple would still occasionally revert back to their bat forms, even after they try to put their past behind them and start a family.
Their children, Rebecca and Aaron, both showed side-effects from their parents' transformations. Rebecca "Becky" Langstrom was born physically nornal, but later showed signs of inheriting Man-Bat's enhanced hearing. Her battles with illnesses would become a constant source of friction between Batman and her father, which usually caused a relapse back into the Man-Bat. In Man-Bat #3 (1996) it was revealed that Francine injected Aaron with the Man-Bat formula in order to save him from a serious illness during infancy, creating Baby-Bat. Both Francine and Becky willingly transformed themselves during the events of No Man's Land in order to protect Aaron from those looking to capitalize on his developing hyper-senses and the Langstroms were all eventually reunited with Kirk. In the end, the Man-Bat family (minus Aaron) was cured by Batman and the parents committed themselves to working on finding a cure that'd give Aaron a human form as well.
Although he's considered a villain by many, Langstorm did attempt to use Man-Bat as a tool for justice. Modifying the serum to not only be able to control his transformations but also to maintain his intelligence as well, Kirk worked as a crime fighter, fighting both regular and super-criminals before transitioning into a career as a private detective. Unfortunately, his career as a crime fighter was constantly marred by personal conflicts, usually involving his family. Kirk would remain on good terms with the Bat Family, usually assisting them when his formula ended up in the wrong hands, like when Talia al Ghul used it to create an army of Man-Bat Commandos.
When the New 52 revised Kirk's backstory, Langstorm suffered not only from the results of his failed cure for the deaf, but also the crippling revelation that Francine had been manipulating him all along so she could develop her own serum. Man-Bat is tragic, modern take on the Jekyll/Hyde dichotomy. Langstrom started out with good intentions, but turned to a life of crime instead. Despite now being cured, the two identities will forever be entangled.