Alexander Fleming was a Scottish microbiologist and physician. He is credited with discovering penicillin, the world's first effective antibiotic substance; a discovery that changed the course of history. He also discovered lysozyme, an antimicrobial enzyme which forms part of the innate immune system. In 1999, Fleming was named in Time magazine's 100 Most Important People of the 20th century list.
Almost 2 decades before germ theory was laid down, Ignaz Semmelweis became the first physician to suggest that hand-washing could prevent the spread of puerperal fever and related deaths. Ironically, after being ridiculed for his theory, he died in a mental asylum, due to an infection from a wound.
Robert Koch was a German microbiologist and physician. One of the prominent co-founders of modern bacteriology, Koch is credited with creating and improving laboratory techniques and technologies in the field of microbiology. He is also credited with making important discoveries in public health. In 1905, Robert Koch won the Nobel Prize in Physiology or Medicine for his research on tuberculosis.
British surgeon Joseph Lister was a pioneer of antiseptic medicine usage and made a huge contribution to the development of preventive medicine for bacterial infection. His achievements have been honored by many, such as the makers of Listerine antiseptic and mouthwash, who named their product after him.
Best known as the father of modern epidemiology, British doctor John Snow revolutionized medical science with his study of London’s Broad Street cholera outbreak of 1854. His research contributed to the development of London’s sewage and water systems and led to the reduction in cholera cases.
German scientist Paul Ehrlich is remembered for his contribution to immunology, which also won him a Nobel Prize. Known as the pioneer of chemotherapy, he also discovered the first-known treatment of syphilis. Born into a business family, he was introduced to the method of studying cells by his pathologist uncle.
Jose Rizal was a Filipino polymath and nationalist. An ophthalmologist by profession, Rizal turned towards writing and inspired the Philippine Revolution through his writings. The revolution eventually led to Philippine independence and Rizal became a national hero. His life has inspired several biographical films and TV series.
10 Ivan Pavlov
Frederick Banting was a Canadian medical scientist and physician. In 1923, Banting and Scottish biochemist John James Rickard Macleod received the Nobel Prize in Medicine for the discovery of insulin and its therapeutic potential. Aged 32 at that time, Banting remains the youngest Nobel laureate in physiology or medicine. He was knighted by King George V in 1934.
14 Alfred Adler
Alfred Adler was an Austrian psychotherapist and medical doctor. He is credited with founding the school of individual psychology. He was also one of the founders of the psychoanalytic movement along with Sigmund Freud and Freud's colleagues. In 2002, a survey conducted by Review of General Psychology named Adler among the 20th century's most eminent psychologists.
Rudolf Virchow was a German physician, pathologist, anthropologist, biologist, prehistorian, editor, writer, and politician. Nicknamed the Pope of medicine by his colleagues, Virchow is credited with founding the field of social medicine. He is also widely regarded as the father of modern pathology. Rudolf Virchow was the first person to name diseases, such as thrombosis, leukemia, ochronosis, embolism, and chordoma.
Scottish surgeon Robert Liston worked in an era when anesthesia wasn’t invented. He could complete amputations within minutes, thus saving the lives of many when the speed of the surgery made the difference between life and death. Later, he became the first European surgeon to operate under anesthesia.
The son of a musician, Emil Kraepelin, remembered as the founder of psychiatry, was the first to differentiate between dementia praecox, now known as schizophrenia, and manic-depressive psychosis. His classification of mental illnesses influenced much of the research on the subject in the 20th century.
Known as The Father of Modern Gynaecology, J. Marion Sims is remembered for developing a surgical method to deal with vesicovaginal fistula, a childbirth-related complication. However, since his experiments were conducted on Black slave-women, without anesthesia, they were later deemed unethical. He had also headed the American Gynecological Society.
Mary Edwards Walker, or Dr. Mary Walker, was the only female surgeon who served injured soldiers during the American Civil War. A dress reform supporter, she believed women should value comfort more than tradition when it came to clothes. She was also the first and only Medal of Honor winner.
22 Henry Gray
Best known for his iconic medical textbook Gray's Anatomy, surgeon Henry Gray, who was a skilled anatomist, was made a Fellow of The Royal Society at the tender age of 25. His untimely death at 34 due to small pox, while treating his nephew, cheated him of an illustrious career.
Popular with German elite for his unconventional treatment, Theodor Gilbert Morell came in contact with Adolf Hitler through Heinrich Hoffmann. Soon appointed the Chancellor’s personal physician, Morell remained with him for the last nine years of his life, helping him in his every day routine, receiving lucrative business contracts in return. Although arrested after the war, he was never convicted.
Otto Heinrich Warburg was a German medical doctor and physiologist. In 1931, his discovery of the nature of the respiratory enzyme earned him the prestigious Nobel Prize in Physiology or Medicine. He also played an important role during World War I where he served as an officer in the cavalry regiment; he was honored with the Iron Cross for bravery.
William Stewart Halsted was the man behind the first American surgical school at the Johns Hopkins University. The master surgeon made a number of contributions to medical science, including the introduction of mastectomy and aseptic surgical procedures. He often injected cocaine into his body to develop anesthesia.
German psychiatrist and neuropathologist Alois Alzheimer is noted for identifying the first published case of presenile dementia, which his colleague and German psychiatrist Emil Kraepelin later identified as Alzheimer's disease. Alois publicly discussed his findings on brain pathology and symptoms of presenile dementia in late-1906 and penned a larger paper giving details of the disease and his findings in 1907.
A descendant of Pennsylvania founder William Penn through his mother, Hermann von Helmholtz studied medicine, pushed by his father, in spite of being interested in the natural sciences. Best known for his law of conservation of energy, he coalesced the fields of medicine, physiology, math, and physics in his studies.
Neuroscientist Wilder Penfield redefined medical science with his innovative way of treating epilepsy patients through surgery. He would note down his patients’ responses when they would be conscious under local anesthesia. He also founded the Montreal Neurological Institute, but was unable to cure his sister’s brain cancer.
Not many suspected physician John Bodkin Adams of being a serial killer till it was revealed that his name had appeared in the wills of at least 132 of his patients who had died, while 163 died in coma. Though never convicted of the killings, he faced punishment for forgery.
31 Ronald Ross
Nobel Prize-winning British doctor Ronald Ross is best remembered for his pathbreaking work on malaria, which proved that the disease was caused by the Anopheles variant of mosquitoes. After his extensive research in India, he went back to London, where he was knighted. He also wrote poetry and songs.
32 Samuel Mudd
Canadian thoracic surgeon Norman Bethune served as an army physician for the Canadian Army during World War I. He revolutionized medical science by introducing the concept of mobile blood-transfusion. A Communist Party of Canada member, he later served the Chinese army against Japan, becoming a revered name in China.
34 Walter Reed
35 Eduard Bloch
Jewish doctor Eduard Bloch began his career as a physician for the Austrian Army. He had later treated a young Adolf Hitler and his cancer-stricken mother, charging very little fees owing to their poor financial condition. This act that made Hitler grant Bloch special protection during the Nazi attack on Austria.
While he apprenticed as a cobbler and a barber in childhood, Santiago Ramón y Cajal later took up medicine inspired by his father, a professor of anatomy. Cajal’s study of the microscopic structure of the human brain later formed the basis of neuroscience and earned him a Nobel Prize.
39 Franz Mesmer
Though a doctor, Franz Mesmer studied the influence of astronomical bodies on the human body and on an invisible fluid inside it. He was a pioneer of animal magnetism, or mesmerism, which paved the path for modern-day hypnotism. Critics slammed his ideas and called him a fraud, too.
The first female doctor and surgeon of Britain, Elizabeth Garrett Anderson was initially denied admission to medical schools because of her gender and had thus started studying privately. Soon after joining the Marylebone Dispensary as an attendant, she contributed to the formation of the New Hospital for Women.
Hudson Taylor was one of the most popular Christian missionaries in China. His 51-year stint in China witnessed him baptizing over 50,000 people. Apart from converting people, he also mingled with the Chinese at a personal level, adopting their clothing habits, contrary to what other missionaries practiced.
William Chester Minor was an army surgeon and lexicographical researcher. He studied at Yale Medical School and earned a medical degree with a specialization in comparative anatomy. He then became an army surgeon. He was later committed to a London psychiatric hospital for many years as he suffered from paranoid delusions. He became a lexicographical researcher while incarcerated.
Howard Florey was an Australian pathologist and pharmacologist. He is best remembered for his role in the formation of penicillin, for which he shared the prestigious Nobel Prize in Physiology or Medicine with Alexander Fleming and Ernst Chain in the year 1945. Florey is credited with carrying out the first clinical trial of penicillin at the Radcliffe Infirmary in 1941.
Havelock Ellis co-wrote the first English textbook on homosexuality. Initially a teacher in Australia, he later moved to London to study medicine. His seven-part Studies in the Psychology of Sex is a first-of-its-kind study on human sexuality. He also believed in eugenics and the importance of smell in sexual behavior.
Immanuel Velikovsky is remembered for his concepts such as cosmogony. He initially studied medicine and psychology, and later devoted his life to his research on ancient myths and legends, attempting to establish their historical authenticity. In spite of facing the hostility of scientists, his Worlds in Collision became a bestseller.
French social psychologist Gustave Le Bon is best remembered for his research on crowd psychology. In his iconic work La psychologie des foules, or The Crowd, he stated that people are driven by their emotions and not by their intellect when they act as part of a crowd.
50 Max Gerson
German-American physician Max Gerson was the proponent of the Gerson Therapy, which began as a diet-based treatment for migraine but ended up being used by him as a treatment for tuberculosis and cancer. Though Gerson died of pneumonia, there was an alternate theory that stated he had been murdered.