Oliver Smithies (born June 23, 1925) is a British-born American geneticist and Nobel laureate, credited with the invention of gel electrophoresis in 1955, and the simultaneous discovery, with Mario Capecchi and Martin Evans, of the technique of homologous recombination of transgenic DNA with genomic DNA, a much more reliable method of altering animal genomes than previously used, and the technique behind gene targeting and knockout mice.

Seeking a new way to correct genetic defects that can cause disease, geneticist Oliver Smithies spent three years trying to introduce short snippets of manipulated deoxyribonucleic acid (DNA) into mammalian cells in the laboratory. His colleagues doubted that his work was feasible, and the graduate students who worked with him at the project's beginning faded away as failure recurred. Smithies was alone in 1985, in a pitch-black darkroom developing x-rays of microscopic images, when he saw that he had successfully inserted an additional gene exactly where and how he wanted it.

His "gene targeting" technique allowed individual genes to be altered at the cellular level. In combination with the work of Martin Evans, Smithies' work led to the breeding of so-called "knock-out mice", animals with controlled pathologies passed from generation to generation, allowing scientific studies of an individual gene's impact. Smithies won the Nobel Prize for Medicine in 2007, an honor shared with Evans and Mario Capecchi, who had conducted similar research independently.

Awards and honors:

Lasker Award 2001 (with Mario Capecchi and Martin Evans)
Wolf Prize in Medicine 2003 (with Ralph L. Brinster and Mario Capecchi)
Nobel Prize for Medicine 2007 (with Mario Capecchi and Martin Evans)
American Academy of Arts and Sciences
American Association for the Advancement of Science
American Chemical Society
National Academy of Sciences 1971
Royal Society Foreign Member
Naturalized US Citizen