Little is known about the early life of the man who goes by the name Doctor Moon. Indeed it is suspected that his title is unearned as no record of his accreditation can be found. "Genius can neither be confirmed or denied by a piece of paper" says Moon. In his mind, the acquisition of knowledge was more important than moral ethics. Dr. Moon is easily the Asian equivalent of the infamous Nazi surgeon Dr. Joseph Mengele.
However, Moon's skills as a surgeon cannot be questioned since he was nominated for a Nobel Prize. Unfortunately, his outrageous experiments and over-sized ego have always put him on the wrong side of the law. "Law is nothing more than the weight of common opinion," he says. After being ostracized from the medical community, Dr. Moon began to lend his expertise to other nefarious enterprises.
Moon has been hired to use his unorthodox medical skills in one nefarious scheme after another. That these schemes constantly violate the Hippocratic oath does not seem to bother Moon. "Only a fool is bound by the words of one who is long dead", he says. Over the years, Moon has travelled from job to job, usually operating in secret. Batman was the first to encounter Dr. Moon during his confrontation with Ra's al Ghul. Dr. Moon conducted experiments under the Demon Head's direction.
Dr. Moon indulged his sick, scientific whims by removing the brain of Dr. Mason Sterling, a scientist in computer engineering. Dr. Moon intended to link Sterling's mind with a computer. Ra's wanted to see if this process was plausible because he wanted to find alternative method for achieving immortality. Fortunately, Batman interrupted the experiment but Dr. Moon got away and Ra's al Ghul's plan to cheat death was denied.
Dr. Moon then entered the employ of the scarred Dr. Cyber. On three separate occasions, Dr. Moon and Dr. Cyber attempt to trap Wonder Woman and remove her brain so Dr. Cyber can implant her mind in Diana's beautiful yet powerful body but they failed each time. Dr. Moon became fascinated by metahumans and wanted to create his own super powered warriors. He established an athletic academy in Gotham and his only success was a man named Topper but Topper was met with defeat by Richard Dragon and Lady Shiva.
Despite Topper's failure, Dr. Moon was still determined to create his own race of metahumans and General Ivan Angst was going to see to it that he succeeded. Gen. Angst wanted to create an army of super powered mercenaries that could rival Ra's al Ghul's League of Assassins. Gen. Angst established Mercenaries Inc and Dr. Moon's metahuman experiments went a step further than they did with Topper. This time, Dr. Moon severed the nerve endings in each of his subjects so they couldn't experience any pain during battle. Fortunately, Batman put an end to Mercenaries Inc but Dr. Moon got away yet again.
Dr. Moon resurfaced when Tobias Whale paid him to extract Halo's memories from her mind. Tobias wanted to know the identities of each member of the Outsiders including Batman's but the Outsiders rescued their teammate and Dr. Moon fled to Gotham. Dr. Moon was then approached by the Joker. Joker was well aware that after Catwoman's reform, she began to have strong affections for Batman and Joker wanted Dr. Moon to manipulate Selina thereby returning her to villainy.
Dr. Moon's compensation for his services was a box of Cuban exploding cigars. Dr. Moon was hardly amused but he still took the job because he too wanted to get even with the Batman for his past interference. Joker kidnapped Catwoman and Dr. Moon used his altered catscan equipment to test Selina's threshold for pain. The process was a success despite Batman's arrival. Both Joker and Dr. Moon were arrested but Batman wanted Dr. Moon for interrogation. Batman demanded and threatened Dr. Moon to reverse what he did to Catwoman but Dr. Moon wouldn't submit to Batman's scare tactics. Catwoman's return to villainy was Dr. Moon's masterpiece of revenge towards the Batman and he will leave it untouched.
Dr. Moon was then moved from Blackgate to Belle Reve Prison, the headquarters of the Suicide Squad. His transfer was authorized by Amanda Waller because she wanted Dr. Moon to erase Plastique's memories of Task Force X. His efforts awarded him a pardon from Belle Reve and a recommendation to the Sunderland Corporation. As an employee of The Sunderland Corporation, Dr. Moon again indulged himself in illegal research activities. At first, his methods seemed benevolent when he amplified Air Wave's abilities and transformed him into Maser. Moon also took advantage of Sunderland's superior technological resources while assisting Deadline. Dr. Moon created other super powered criminals which brought the attention of Hawkman.
He later left Sunderland and joined Intergang. Dr. Moon was ordered to wipe the mind of Catherine Grant who had information that could bring down Intergang. Dr. Moon was successful despite the joint effort of Superman and Batman. Cat Grant was unable to testify in court but Dr. Moon left Intergang because he had to speak up more than once by questioning the organization's methods.
Dr. Moon returned to Gotham and took a job for Two-Face. It turns out Gilda Dent had taken an experimental fertility drug before she was committed after the Holiday murders. Gilda gave birth to conjoint twins while she was institutionalized and Harvey managed to steal them. Dr. Moon was hired to separate Harvey's conjoint twins. Unfortunately, Batman interfered and in a fit of rage Two-Face shoots Dr. Moon in his left shoulder.
Batman asked why Dr. Moon does not use his obvious skills to heal the sick and Moon replies, "Healing is the body's natural process, and is therefore dull and commonplace. I am an experimenter - a pioneer, a misunderstood visionary." Afterwards, the police of six continents came in to interrogate Doctor Moon about his past activities. Dr. Moon managed to escape custody and shacked up with Phobia in an Injustice Society's satellite station. Merlyn stated that whenever Dr. Moon and Phobia came to the satellite hangout, someone would always wind up missing.
Dr. Moon's last job was to perform an organ transplant for Walter Pratt, Kate Spencer's father. Kate Spencer aka Manhunter gets into a hand to hand combat situation with Dr. Moon in the dark. Despite Moon's night vision glasses, Kate got the upper hand and stabs Moon in the neck with his scalpel. The doctor bleeds to death thus ending his career in unorthodox medicine.
Justice League Unlimited
Doctor Moon appears in the Justice League Unlimited episode "Question Authority", but his voice actor is uncredited. He appears as a member of Project Cadmus replacing Hugo Strange, who could not be used because of the Bat-embargo. His task was to determine how much information the Question had read from the Cadmus files. Moon using a machine that makes the Question see what will happen if the Justice League went rogue like the Justice Lords. The Question resisted long enough to be rescued by Superman and the Huntress. Moon offered no resistance, but was still nearly killed by Huntress's crossbow, spared by Superman's intervention. He also makes cameo appearances in "Flashpoint".