Hamilton Othanel Smith (born August 23, 1931) is an American microbiologist and Nobel laureate.

Smith was born on August 23, 1931, and graduated from University Laboratory High School of Urbana, Illinois. He attended the University of Illinois at Urbana-Champaign, but in 1950 transferred to the University of California, Berkeley, where he earned his B.A. in Mathematics in 1952 . He received his medical degree from Johns Hopkins University in 1956. In 1975, he was awarded a Guggenheim Fellowship he spent at the University of Zurich.