Hanaoka Seishu (1760-1835), was a Japanese physician during the Edo Period who was the first ever to successfully put a patient under general anesthesia during surgery, 40 years before the first widely publicized such feat was accomplished by Western physicians at Massachusetts General Hospital in Boston.
Whereas various kinds of local anesthetic had been used for centuries in both the East and the West, general anesthesia is much more complex, and involves putting a patient into total unconsciousness for a sustained period of time and then successfully reviving them afterward. Whereas the doctors at MGH in Boston would use the synthetic gas ether, Seishu's approach was to use a concoction of naturally occurring herbs including digitalis and deadly nightshade. Interestingly, while ether is no longer used as an anesthetic in developed countries because it is highly flamable and has numerous undesirable side effects, the class of drug Seishu invented 40 years earlier in a small town in Japan is still often used to this day.
The problem Seishu faced in developing such a drug, of course, was that most of the herbs he was dealing with are highly toxic. The trick was to figure out the exact combination of minute dosages which would put a person unconscious for a time, but not entirely kill them. To this end, Seishu spent 20 years experimenting with different dosages on his own wife. According to the story, when Seishu was asked why he didn't experiment on his aged mother instead, Seishu replied that if his wife died, he could always remarry, but that he only had one mother.
Eventually Seishu finally found the perfect cocktail of herbs to successfully induce general anesthesia, but at the horrific cost of his wife becoming permanently blind. In 1804 he successfully performed a breast cancer removal surgery on a 60-year-old woman while putting her under general anesthesia, and later would successfully perform hundreds more successful operations using the drug.
Although Seishu was relatively famous in his own time, drawing patients from all across the Japanese Isles to receive his revolutionary treatment, he later faded into obscurity, and for many years the doctors at MGH in Boston were celebrated as the first to achieve general anesthesia. Later it was discovered that Dr. Crawford Long of Georgia had actually used ether successfully a few years earlier, but finally Japanese scholars uncovered Seishu and publicized his achievements to the world, and today he is recognized worldwide as the "father of anesthesia." His original house/clinic is preserved as a museum in Wakayama prefecture in Japan, and much has been made of the tragic tale of his wife, which became the subject of a famous fictionalized account in the 1966 Japanese novel (and ensuing TV minseries) The Doctor's Wife.