When Kirk Langstrom was a young boy, he fell into a deep cavern and was lost for more than six weeks. Police conducted a massive search for the child, and were nearly ready to give up when they finally found him. Though his parents were overjoyed to see their son returned to them, Kirk seemed almost sorry to leave the cave. He silently waved goodbye to the "friends" he left behind.
A short time later, Kirk met six-year-old Bruce Wayne outside of a movie theater. He regaled Bruce with tales of his adventures beneath the earth, and embellished such tales by telling him about the race of half-human, half-bat creatures he encountered.
As an adult, Kirk left his home town of Chicago and enrolled at Gotham University where he met fellow student Francine Lee. Even after all this time the so-called "cave boy" was still obsessed with bats, and he believed that he could pioneer new medical breakthroughs through the study of bats. 
After college, Kirk became a zoologist and nocturnal mammals expert employed by the Gotham Natural History Museum. He long admired the careers of costumed crime fights and wanted to emulate, particularly those such as the legendary Batman. To this end, Langstrom used his scientific knowhow to develop a serum extracted from the glands of bats. This serum was designed to amplify a person's sensory capabilities, gifting them with enhanced hearing. Like many scientists of his caliber, Langstrom decided to test the serum on himself with immediate results. His hands grew hairy and claw-like and his face took on the physical characteristics of a bat – including elongated ears that allowed him to perceive his surroundings via echolocation.
Dubbing himself the Man-Bat, Langstrom first went into action when a group of thieves calling themselves the Blackout Gang broke into the museum. Batman was on their trail and the Man-Bat teamed up with him to bring the thieves down. Batman welcomed the assistance, but the Man-Bat shied away when Batman mistakenly complimented him on his "disguise". As the Man-Bat ran off, Batman wondered if he had just made a formidable ally – or a brand new adversary.  A short time later, Langstrom attempted to break into Biochem, Ltd. after learning that they possessed a possible cure for his mutation inside one of their vaults. As luck would have it, a gang of thieves decided to rob Biochem on the very night that Langstrom planned to strike. Their presence brought the Batman down upon them and Man-Bat and Batman teamed up once again to stop the criminals. When the fight was over however, Man-Bat still intended on stealing the formula that he had come there to acquire. Batman could not allow this and the two came to blows for the very first time. Man-Bat knocked Batman out cold and ran off into the night.
When Batman came to, he instinctively thought that Man-Bat might return to the place where they first met – the Gotham Museum of Natural History. Arriving there, Batman met Kirk Langstrom's fiancée, Francine Lee. It was then that he deduced that Langstrom and the Man-Bat were one and the same. He burst into Langstrom's laboratory just as the Man-Bat was preparing to consume the formula that he has stolen. Batman's presence startled him and he dropped the beaker where it smashed upon the floor. The Man-Bat then leapt from a third-story window and the Batman gave chase. As he pursued Man-Bat towards the cliffs, Langstrom hurled himself off the edge. Plummeting towards the river below, he entered the next phase of his mutation by sprouting leathery, bat-like wings under his arms. With that, the Man-Bat was able to fly away to safety.
Man-Bat took shelter inside of a tight crevice in the side of a cliff. He soon discovered that the crevice opened up into a greater cavern which led all the way to the Batcave. When Batman returned home, the Man-Bat tried to escape, but Batman sealed off the cave, eventually incapacitating Langstrom. He then administered his own special chemical compound, which he had hoped would cure Langstrom of his mutated condition. 
The Man-Bat awakened during the procedure and flew into the darker recesses of the cave. The Batman left to find Francine Lee, hoping that she might be able to calm Langstrom down long enough for him to administer the cure. When he returned to the Batcave with Francine however, the Man-Bat was gone.
Langstrom tracked Francine down several weeks later. His sanity began to suffer by this point, and he rejected the concept of being cured. He now believed that he was superior to Batman and all other human beings. He reunited with Francine who professed to love him regardless of his condition. The Man-Bat made Francine prove her love for him by subjecting her to the same bat gland extract that first turned him into the Man-Bat. Now they were both creatures of the night.  Added by Brian KurtzThe Batman caught up with Kirk and Francine on the night of their wedding. He burst into the cathedral, removed the latex masks they had been wearing and exposed their monstrous features before all of the attending wedding guests. The guests fled the hall in terror and Batman had to take on not one, but two savage Man-Bats. Scaling the steps of the cathedral, he used the church’s great bell to disorient the Man-Bats, giving him the opportunity to incapacitate them and inject them with his cure. Kirk and Francine appeared to be normal now and could live out the rest of their days as a normal married couple. 
A series of chance occurrences lead Kirk Langstrom to relapse into his Man-Bat identity after marrying Francine Lee, and the Batman had to capture him and restore him to normalcy. 
A few months later, Doctor Langstrom and Francine were called out to the deserts of Nevada to investigate the sudden appearance of a rare breed of tropical vampire bats. Langstrom deduced that their sudden presence in Nevada was caused by atomic bomb testing beneath the desert sands of New Mexico – testing that disrupted a network of warrens, forcing the bats to travel further into the desert. While examining the vampire bats, Francine was bitten and reverted to her She-Bat stage, but was now even more monstrous than before. When news of the Langstroms' work in the desert reached the ears of Batman, he came to Las Vegas to investigate. Kirk and Batman corralled the savage Francine Lee inside a cave whereupon Batman ensnared her with his batrope. He then administered the same cure that he had given her before, but with the caveat that she would soon need a full blood transfusion. Kirk wanted to donate his own blood, but Batman wouldn't allow it. Francine and he soon returned to Gotham City. 
Events transpired that prompted Langstrom to take his bat extract serum once again. This time however, he maintained his personality and did not seem to suffer from the insanity that had previously gripped him. With greater control over his transformations, the Man-Bat committed himself towards becoming a crime-fighter and proved pivotal in bringing down a criminal known as Roy Reynolds. 
Sometime later, Kirk Langstrom learned that the widow of a man named Moran was giving a $100,000 reward for the capture of the man who assassinated her husband. Langstrom needed the money, so he decided to inject himself with his special serum and became the Man-Bat once again.
He traveled to the island of Santa Cruz which was run by a dictator named Domingo Valdez. Man-Bat used his grotesque appearance to convince the islanders that he was a bat-god and ordered them to deal with several CIA agents who were likewise looking to collect on the reward. The Man-Bat flew to Valdez's castle, but he was attacked by vampire bats and forced to retreat. At this time, Langstrom had another encounter with the Batman. The two decided to work together to bring down Killer Krag, the man who assassinated Moran. They tried to infiltrate Valdez's castle but were captured in the process. Langstrom lent Batman some of his serum and Batman transformed into a true "Bat-Man". He then freed Langstrom and together they captured Killer Krag and left Santa Cruz. Back in Gotham, Batman returned to his normal form and donated the reward money to Langstrom's department at the Gotham Natural History Museum. 
Langstrom was later forced to assume the guise of the Man-Bat again – this time to combat a sorcerer calling himself Baron Tyme. Tyme had entered into a bargain with dark forces for power and in exchange, he needed to sacrifice innocent lives. To facilitate this task, Tyme used his power to hypnotize Francine Langstrom, turning back into the She-Bat and using her as his personal assassin. Man-Bat tried several times to stop Francine, but she was even stronger than he was by this point. He enlisted the aid of Batman and together they were able to defeat Baron Tyme and free Francine from his control. 
In order to take better care of his wife, Kirk reluctantly relocated from Gotham City to his home town of Chicago, Illinois. Members of his family and several old friends held a surprise "Welcome Back" party for him, but Kirk had little interest in family gatherings. The only thing that concerned him was seeing after his wife. At this time, the Man-Bat found himself at odds with one of his strangest foes to date: Phil Reardon, the Ten-Eyed Man. Reardon had been hired by a man named Lowell, leader of the Civil Liberties Association to capture the Man-Bat. Lowell promised him that he would perform an experiment to give him the Man-Bat's echolocation powers. The Ten-Eyed Man ambushed the Man-Bat, but Langstrom managed to escape from him near Lake Michigan. They fought against one another a second time on the balcony of Langstrom's apartment. This time however, the Ten-Eyed Man came prepared with a magnesium flare bomb, which he intended on using to blind the Man-Bat. During the fight, the bomb was accidentally triggered prematurely. The Man-Bat thrust Reardon in front of the bomb and he was permanently blinded. Reardon lost his balance and fell from the top of the building, seemingly to his death.  Kirk and Francine remained in Chicago for some time and eventually gave birth to their first child, Rebecca. Everything seemed to be going perfectly for the Langstroms: Francine was cured, Kirk had control over his transformations and they now had a new child to raise.
While still a young child, Rebecca fell deathly ill from a mysterious disease. Batman tried to help the Langstroms, but when he came into possession of the Seronotal needed to save her life, the Batman destroyed it, believing the formula had been tainted. 
Rebecca was eventually saved, but Kirk felt that Batman had betrayed them and had tried to kill his daughter. Whereas Kirk once felt immeasurable respect for Batman, now he felt nothing but hate. His hatred of Batman grew into an obsession and this obsession began to affect his work. In short order, the Langstroms lost their home and their fortune. They were forced to return to Gotham City where they lived in a rundown apartment in Gotham's East End.
One evening, Kirk was working with his bat gland formula when he made a miscalculation in the chemical compound. Upon drinking it, he instantly transformed, but his conscious mind was subsumed, replaced with nothing but raw, naked instinct. He flew off into the night and eventually returned to the catacombs that led to the Batcave. By this point, Batman had relocated to the Wayne Foundation building and his ancestral home, Wayne Manor, was largely abandoned. Occasionally, children or squatters would make their way into the empty house, but they never stayed long. The shrieking cries of the Man-Bat always drove them away.
After several such instances, some began to believe that Wayne Manor was haunted. Commissioner Gordon led a search of the mansion to ferret out the source of these alleged "ghostly wails". Accompanying him was the Batman as well as ghost breaker Doctor Terrence Thirteen. Batman's primary concern was making sure that the original Batcave was safely sealed off from inspection. He came upon the Man-Bat who viciously fought against him. Doctor Thirteen tried to lend a hand, but the Man-Bat knocked him back, hospitalizing him. Batman scooped up Thirteen's sonic radar and turned it on Langstrom, forcing the Man-Bat to flee deeper into the cave.
Batman eventually caught up with him, and as the two struggled against one another, Batman forced him to take the antidote. This time however, the antidote had no effect and the Man-Bat escaped. 
*Transformation: Upon injection of his bat gland extract, Kirk Langstrom can transform himself into a half-human/half-bat creature. Once the serum wears off, the Man-Bat returns back to human form.
- Flight: Man-Bat can fly by way of artificially generated leather wings.
- Claws: The Man-Bat has sharpened claws which are strong enough to easily tear through flesh and muscle.
- Echolocation: Man-Bat can navigate through the air by way of echolocation, similar in function to a bat's radar.===Strength level===
As Langstrom, Kirk possesses the strength level of a man his age, size and weight who engages in minimal regular exercise. As Man-Bat, his strength level is at least double that of a man in good athletic condition.
Man-Bat's hearing is highly sensitive and extremely loud noises cause him great pain. He is also extremely sensitive to bright light, preferring instead to remain in dark locations.
...and the Man-Bat soars!
Added by Zakolj*Although this character was originally introduced during DC's Earth-One era of publication, their existence following the events of the 1985-86 limited series Crisis on Infinite Earths remains intact. However, some elements of the character's Pre-Crisis history may have been altered or removed for Post-Crisis New Earth continuity, and should be considered apocryphal.