Biologists

1. Louis Pasteur  was a French chemist and microbiologist best known for his remarkable breakthroughs in the causes and prevention of disease. His experiments supported the germ theory of disease, also reducing mortality from puerperal fever (childbed), and he created the first vaccine for rabies. He was best known to the general public for inventing a method to stop milk and wine from causing sickness - this process came to be called pasteurization. He is regarded as one of the three main founders of microbiology, together with Ferdinand Cohn and Robert Koch. He is also credited with dispelling the theory of spontaneous generation with his experiment employing chicken broth and a goose neck flask. He also made many discoveries in the field of chemistry, most notably the asymmetry of crystals. He is buried beneath the Institut Pasteur, an incredibly rare honor in France, where being buried in a cemetery is mandatory save for the fewer than 300 "Great Men" who are entombed in the Panthéon.
2. Norman Ernest Borlaug is an American agricultural scientist, humanitarian, Nobel laureate, and has been called the father of the Green Revolution. Borlaug is one of five people in history to have won the Nobel Peace Prize, the Presidential Medal of Freedom and the Congressional Gold Medal.
3. Alfred Russel Wallace, OM, FRS  was a British naturalist, explorer, geographer, anthropologist and biologist. He did extensive field work first in the Amazon River basin, and then in the Malay Archipelago, where he identified the Wallace line dividing the fauna of Australia from that of Asia.
4. Johann Georg Adam Forster was a German naturalist, ethnologist, travel writer, journalist, and revolutionary. At an early age, he accompanied his father on several scientific expeditions, including James Cook's second voyage to the Pacific. His report from that journey, A Voyage Round the World, contributed significantly to the ethnology of the people of Polynesia and remains a respected work among both scientists and ordinary readers. As a result of the report Forster was admitted to the Royal Society at the early age of twenty-two and came to be considered one of the founders of modern scientific travel literature.
5. Rosalind Elsie Franklin was a British physical chemist and crystallographer who made important contributions to the understanding of the fine structures of DNA, viruses, coal and graphite. Franklin is best known for her contribution to the discovery of the structure of DNA in 1953. In the years following, she led pioneering work on the tobacco mosaic and polio viruses. 
6. Barbara McClintock was a pioneering American scientist and one of the world's most distinguished cytogeneticists. 
7. Heinrich Hermann Robert Koch was a German physician. He became famous for the discovery of the anthrax bacillus (1877), the tuberculosis bacillus (1882) and the cholera bacillus (1883) and for his development of Koch's postulates. He was awarded the Nobel Prize in Physiology or Medicine for his tuberculosis findings in 1905. He is considered one of the founders of bacteriology.
8. George Ledyard Stebbins, Jr. was an American botanist and geneticist who is widely regarded as one of the leading evolutionary biologists and botanists of the 20th century.
9. Lynn Margulis is a biologist and University Professor at the University of Massachusetts Amherst. She is best-known for her theory on eukaryotic organelle genesis, the endosymbiotic theory, which is now accepted in the mainstream as the explanation for how certain organelles were formed.
10. Gregor Mendel  was an Austrian monk who is often called the "father of genetics" for his study of the inheritance of traits in pea plants. Mendel showed that there was particular inheritance of traits according to his laws of inheritance. The significance of Mendel's work was not recognized until the turn of the 20th century.