Regarded as the father of psychoanalysis, Sigmund Freud was a neurologist. Despite suffering criticism, psychoanalysis remains influential in the fields of psychology and psychiatry; such is the influence Freud has on humanities. Scholars believe that Freud is one of the most influential personalities of the 20th century and that his impact is comparable to that of Marxism and Darwinism.
Widely regarded as the father of analytical psychology, Carl Jung is one of the most important contributors to symbolization and dream analysis. The concepts of socionics and a popular psychometric instrument called Myers-Briggs Type Indicator (MBTI) were developed from Jung's theory. Apart from working as a psychiatrist and psychoanalyst, Carl Jung was also an artist, craftsman, builder, and prolific writer.
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.
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.
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.
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.
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.
10 Jose Rizal
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.
11 John Snow
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.
Johns Hopkins Hospital co-founder William Osler was also an avid historian. He redefined medical education with his emphasis on clinical experience and his book The Principles and Practice of Medicine. Born to a missionary father in Canada, he was to follow in his father’s footsteps but decided to study medicine instead.
13 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.
Albert Schweitzer was an Alsatian polymath who won the Nobel Peace Prize in 1952 for his philosophical work, Reverence for Life. He is credited with founding the Albert Schweitzer Hospital, which was a direct result of his philosophical expression. Schweitzer is also credited with influencing the Organ reform movement, which began in the mid-20th-century.
18 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.
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.
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.
Though she was married off at age 9 and had had a baby by 14, Anandi Gopal Joshi rose to become one of the first female doctors in India and the first Indian-origin woman to graduate with a medical degree in the US. Unfortunately, she died of tuberculosis shortly before her 22nd birthday.
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.
28 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.
29 Karen Horney
Remembered for her pioneering work on feminist psychology, Karen Horney studied medicine at a time when women weren’t allowed in universities. Going against Sigmund Freud’s concept of penis envy, she suggested the idea of womb envy. She believed psychological differences weren’t rooted in gender but rather depended on the socio-cultural influences.
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.
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.
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.
34 Samuel Mudd
The founder of homeopathy, Samuel Hahnemann was a qualified physician but disapproved of medical practices such as bloodletting that were used back then. He thus formed his system of alternative medicine. The apathy of his fellow physicians in Leipzig forced him to move first to Köthen and then to Paris.
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.
37 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.
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.
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.
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.
42 Walter Reed
43 A. J. Cronin
44 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.
47 John McCrae
Best known for his iconic war poems such as In Flanders Fields, Canadian poet John McCrae was also an army physician. He was the first Canadian to serve as a consulting surgeon for the British Army and had earned the rank of Lieutenant Colonel in the Canadian Army.
48 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.
Daniel Hale Williams was a general surgeon known for performing the first documented, successful pericardium surgery in the US in 1893. Born to interracial parents, he faced numerous struggles in his journey to become a physician. He later founded the first non-segregated hospital in the United States, Chicago's Provident Hospital. He also founded a nursing school for African Americans.
American neurologist Walter Jackson Freeman II is remembered for co-developing the technique of prefrontal lobotomy as a treatment for mental ailments, along with neurosurgeon James W. Watts. Though many of his patients died due to the treatment, he is still considered a pioneer in the field of neurosurgery.