Biologists, or those who study biology, have contributed many of the greatest findings in science. A biologist might study anything from cells to human evolution, but their focus always relates back to the study of life.

McCollum, Elmer Verner (1879-1967), a United States physiological chemist. McCollum was one of the discoverers of vitamins A, B, and D, between the years 1912 and 1922.

Wieschaus, Eric Francis (1947-), an American biologist, has studied how genes affect early embryo development.

Kandel, Eric Richard (1929-) won the 2000 Nobel Prize in physiology or medicine—along with scientists Arvid Carlsson of Sweden and Paul Greengard of the United States—for his research on the function of brain cells in learning and memory.

Just, Ernest Everett (1883-1941) was an internationally known American biologist, zoologist, and physiologist who made major contributions to the field of biology through his pioneering research into fertilization, experimental parthenogenesis, and cell physiology.

Mayr, Ernst (1904-2005) was a German-born American biologist who helped develop the synthetic theory of evolution, which combines evolution theory with genetics and other sciences.

Sabin, Florence Rena (1871-1953), a United States physician and medical researcher.

Collins, Francis (1950-) is an American physician and geneticist who in the late 1900's became recognized as one of the most important and talented figures in the field of medical genetics.

Stahl, Franklin William (1929-) is an American geneticist and expert in the field of bacteriophages, parasitic viruses that multiply within their host bacteria.

Lipmann, Fritz Albert (1899-1986), an American biochemist, shared the 1953 Nobel Prize in physiology or medicine.

Schaller, George Beals (1933-), is a German-born American zoologist, a scientist who studies animals.

Snell, George Davis (1903-1996) was an American geneticist who discovered the genes responsible for the rejection of tissue transplants.

Wald, George (1906-1997) was an American biochemist who discovered how chemical changes in the retina enable a person to see.

Beadle, George Wells (1903-1989) shared the 1958 Nobel Prize in physiology or medicine with biochemists Edward Lawne Tatum and Joshua Lederberg for discovering that genes regulate specific chemical processes in cells.

Edelman, Gerald Maurice (1929-) is an American physiologist. He shared the 1972 Nobel Prize in physiology or medicine with British physiologist Rodney Robert Porter for their discovery of the basic chemical structure of antibodies.

Elion, Gertrude Belle (1918-1999) was an American biochemist who won the Nobel Prize in physiology or medicine in 1988 for the development of the antiviral drug acyclovir for the treatment of cancer.

Stent, Gunther Siegmund (1924-) is a leading German-born American molecular biologist.

Hartline, Haldan Keffer (1903-1983) was an American physiologist. He shared the 1967 Nobel Prize in physiology or medicine for his work on the neuro-physiology of vision.

Smith, Hamilton Othanel (1931-) is an American microbiologist who made breakthrough discoveries related to enzymes, the molecules that speed up the chemical reactions in all living things.

Varmus, Harold Eliot (1939-) is an American physician and cancer researcher who shared the 1989 Nobel Prize in physiology or medicine with his colleague J.

Gasser, Herbert Spencer (1888-1963), an American physiologist, carried out research that helped identify the functions of different fibers in the same nerve.

Muller, Hermann Joseph (1890-1967), a United States geneticist. Experimenting with fruit flies, Muller found that mutations (changes in the structure of the genes) can be produced by X rays.

Swift, Hewson Hoyt (1920-2004) was an American microbiologist. His research on cell biology and genetics contributed to the understanding of the structure of chromosomes and the function of DNA.

Temin, Howard Martin (1934-1994) was an American molecular biologist and virologist who discovered that genetic information in ribonucleic acid (RNA) can be copied into deoxyribonucleic acid (DNA).

J. Craig Venter, an American biochemist and businessman, is a pioneer in research on the human genome, the genetic instructions that control heredity in humans.

Bishop, J. Michael (1936-), an American cancer researcher, investigated oncogenes, or tumor-producing genes, turning over previously held theories about how cancer develops.